The file at location /usr/share/X11/xkb/symbols/bd contains the following as the last lines:

//

// XKB symbol :: Probhat Bangla/Bengali Keyboard Layout

// Ref: www.ankurbangla.org/images/probhat_layout.png

//



xkb_symbols "probhat" {

include "in(ben_probhat)"

name[Group1]= "Bangla (Probhat)";

};

In your case if I understand correctly, you should not edit this file but instead the file layout at location /usr/share/X11/xkb/symbols/in

Locate the lines:

xkb_symbols "ben_probhat" {

name[Group1]= "Bangla (India, Probhat)";

Thereupon, starting the new layout remapping.

Note that you don't need to remap each keys 1 by 1 again because the unicodes for your language are already set for this layout! You only need to reorder the keys and this works for any languages and/or layouts whose phonetics are based on qwerty and the user rather wants to map it to standard dvorak.

In your case the file /usr/share/X11/xkb/symbols/in looks like this:

xkb_symbols "ben_probhat" {

name[Group1]= "Bangla (India, Probhat)";

key <ESC>  { [ Escape ] };



// numbers

key <TLDE> { [ U200D, asciitilde   ] };

key <AE01> { [ U09E7, exclam       ] };

key <AE02> { [ U09E8, at           ] };

key <AE03> { [ U09E9, numbersign   ] };

key <AE04> { [ U09EA, U09F3    ] };

key <AE05> { [ U09EB, percent      ] };

key <AE06> { [ U09EC, asciicircum  ] };

key <AE07> { [ U09ED, U099E    ] };

key <AE08> { [ U09EE, U09CE    ] };

key <AE09> { [ U09EF, parenleft    ] };

key <AE10> { [ U09E6, parenright   ] };

key <AE11> { [ minus,     underscore   ] };

key <AE12> { [ equal,     plus         ] };

key <BKSP> { [ BackSpace               ] };



// tab, q to ] 

key <TAB>  { [   Tab,  ISO_Left_Tab     ] };

key <AD01> { [   U09A6,  U09A7  ] };

key <AD02> { [   U09C2,  U098A  ] };

key <AD03> { [   U09C0,  U0988  ] };

key <AD04> { [   U09B0,  U09DC  ] };

key <AD05> { [   U099F,  U09A0  ] };

key <AD06> { [   U098F,  U0990  ] };

key <AD07> { [   U09C1,  U0989  ] };

key <AD08> { [   U09BF,  U0987  ] };

key <AD09> { [   U0993,  U0994  ] };

key <AD10> { [   U09AA,  U09AB  ] };

key <AD11> { [   U09C7,  U09C8  ] };

key <AD12> { [   U09CB,  U09CC  ] };

key <RTRN> { [   Return                 ] };



// caps, a to ' 

//   key <CAPS> { [   Caps_Lock              ] };

key <AC01> { [   U09BE,  U0985  ] };

key <AC02> { [   U09B8,  U09B7  ] };

key <AC03> { [   U09A1,  U09A2  ] };

key <AC04> { [   U09A4,  U09A5  ] };

key <AC05> { [   U0997,  U0998  ] };

key <AC06> { [   U09B9,  U0983  ] };

key <AC07> { [   U099C,  U099D  ] };

key <AC08> { [   U0995,  U0996  ] };

key <AC09> { [   U09B2,  U0982  ] };

key <AC10> { [   semicolon,  colon      ] };

key <AC11> { [   apostrophe, quotedbl   ] };



// shift, z to /

//   key <LFSH> { [   Shift_L                ] };

key <AB01> { [   U09DF,  U09AF  ] };

key <AB02> { [   U09B6,  U09DD  ] };

key <AB03> { [   U099A,  U099B  ] };

key <AB04> { [   U0986,  U098B  ] };

key <AB05> { [   U09AC,  U09AD  ] };

key <AB06> { [   U09A8,  U09A3  ] };

key <AB07> { [   U09AE,  U0999  ] };

key <AB08> { [   comma,      U09C3  ] };

key <AB09> { [   U0964,  U0981  ] };

key <AB10> { [   U09CD,  question   ] };

key <BKSL> { [   U200C,  U0965  ] };

This gives this layout

Now you just need to reorder the keys like this:

// numbers

key <TLDE> { [ grave,   asciitilde, voidsymbol, voidsymbol ] };

key <AE01> ==> key <AE01> <== NO CHANGE!

key <AE02> ==> key <AE02> <== NO CHANGE!

key <AE03> ==> key <AE03> <== NO CHANGE!

key <AE04> ==> key <AE04> <== NO CHANGE!

key <AE05> ==> key <AE05> <== NO CHANGE!

key <AE06> ==> key <AE06> <== NO CHANGE!

key <AE07> ==> key <AE07> <== NO CHANGE!

key <AE08> ==> key <AE08> <== NO CHANGE!

key <AE09> ==> key <AE09> <== NO CHANGE!

key <AE10> ==> key <AE10> <== NO CHANGE!

key <AE11> ==> key <AC11>

key <AE12> ==> key <AD12>

key <BKSP> { [ BackSpace ] };



// key <TAB>  { [ Tab,  ISO_Left_Tab ] };

key <AD01> ==> key <AB02>

key <AD02> ==> key <AB08>

key <AD03> ==> key <AC03>

key <AD04> ==> key <AD09>

key <AD05> ==> key <AC08>

key <AD06> ==> key <AD05>

key <AD07> ==> key <AC04>

key <AD08> ==> key <AC05>

key <AD09> ==> key <AC02>

key <AD10> ==> key <AD04>

key <AD11> ==> key <AE11>

key <AD12> ==> key <AE12>

key <RTRN> { [ Return ] };



// key <CAPS> { [ Caps_Lock ] };

key <AC01> ==> key <AC01> <== NO CHANGE!

key <AC02> ==> key <AC10>

key <AC03> ==> key <AC06>

key <AC04> ==> key <AD06>

key <AC05> ==> key <AD07>

key <AC06> ==> key <AC07>

key <AC07> ==> key <AB03>

key <AC08> ==> key <AB04>

key <AC09> ==> key <AD10>

key <AC10> ==> key <AB01>

key <AC11> ==> key <AD01>



// key <LFSH> { [ Shift_L ] };

key <AB01> ==> key <AB10>

key <AB02> ==> key <AB05>

key <AB03> ==> key <AD08>

key <AB04> ==> key <AB09>

key <AB05> ==> key <AB06>

key <AB06> ==> key <AC09>

key <AB07> ==> key <AB07> <== NO CHANGE!

key <AB08> ==> key <AD02>

key <AB09> ==> key <AD03>

key <AB10> ==> key <AD11>

key <BKSL> { [ backslash,   bar,        voidsymbol, voidsymbol ] };

So that it looks like below in the file /usr/share/X11/xkb/symbols/in

xkb_symbols "ben_probhat" {

name[Group1]= "Bangla (India, Probhat)";

key <ESC>  { [ Escape ] };



// numbers

key <TLDE> { [ U200D, asciitilde   ] };

key <AE01> { [ U09E7, exclam       ] };

key <AE02> { [ U09E8, at           ] };

key <AE03> { [ U09E9, numbersign   ] };

key <AE04> { [ U09EA, U09F3    ] };

key <AE05> { [ U09EB, percent      ] };

key <AE06> { [ U09EC, asciicircum  ] };

key <AE07> { [ U09ED, U099E    ] };

key <AE08> { [ U09EE, U09CE    ] };

key <AE09> { [ U09EF, parenleft    ] };

key <AE10> { [ U09E6, parenright   ] };

key <AC11> { [ minus,     underscore   ] };

key <AD12> { [ equal,     plus         ] };

key <BKSP> { [ BackSpace               ] };



// tab, q to ] 

key <TAB>  { [   Tab,  ISO_Left_Tab     ] };

key <AB02> { [   U09A6,  U09A7  ] };

key <AB08> { [   U09C2,  U098A  ] };

key <AC03> { [   U09C0,  U0988  ] };

key <AD09> { [   U09B0,  U09DC  ] };

key <AC08> { [   U099F,  U09A0  ] };

key <AD05> { [   U098F,  U0990  ] };

key <AC04> { [   U09C1,  U0989  ] };

key <AC05> { [   U09BF,  U0987  ] };

key <AC02> { [   U0993,  U0994  ] };

key <AD04> { [   U09AA,  U09AB  ] };

key <AE11> { [   U09C7,  U09C8  ] };

key <AE12> { [   U09CB,  U09CC  ] };

key <RTRN> { [   Return                 ] };



// caps, a to ' 

//   key <CAPS> { [   Caps_Lock              ] };

key <AC01> { [   U09BE,  U0985  ] };

key <AC10> { [   U09B8,  U09B7  ] };

key <AC06> { [   U09A1,  U09A2  ] };

key <AD06> { [   U09A4,  U09A5  ] };

key <AD07> { [   U0997,  U0998  ] };

key <AC07> { [   U09B9,  U0983  ] };

key <AB03> { [   U099C,  U099D  ] };

key <AB04> { [   U0995,  U0996  ] };

key <AD10> { [   U09B2,  U0982  ] };

key <AB01> { [   semicolon,  colon      ] };

key <AD01> { [   apostrophe, quotedbl   ] };



// shift, z to /

//   key <LFSH> { [   Shift_L                ] };

key <AB10> { [   U09DF,  U09AF  ] };

key <AB05> { [   U09B6,  U09DD  ] };

key <AD08> { [   U099A,  U099B  ] };

key <AB09> { [   U0986,  U098B  ] };

key <AB06> { [   U09AC,  U09AD  ] };

key <AC09> { [   U09A8,  U09A3  ] };

key <AB07> { [   U09AE,  U0999  ] };

key <AD02> { [   comma,      U09C3  ] };

key <AD03> { [   U0964,  U0981  ] };

key <AD11> { [   U09CD,  question   ] };

key <BKSL> { [   U200C,  U0965  ] };

Ultimately giving the layout I assume you would like

Note that you must make a backup of the original file layout before starting to edit and save it as root or otherwise you'll have to download and restore it back from freedesktop.org/wiki/Software/XKeyboardConfig

Albeit I don't understand nothing from the alphabet, I hope this could help because I've been using the dvorak layout as well for many years and I hope that one day it can replace the qwerty layout from being always the standard :(