In Arabic, there are basically three forms for almost all letters (i.e. Initial Form, Medial Form, and Final Form).
I'm still confused

As one goes in the system while other should be in insert/symbols in MS Word.
Well it shows in the insert/symbols, and for the ease of the typist I created a custom keyboard layout using Microsoft Keyboard Layout Creator and changed the same key(i.e, I) with shift+I for the alternate final form.
Now, in both the case, 1) Insert symbol, and 2) Shift+I with the custom keyboard, the character(alternate heh doachashmee) comes and is placed properly, but the problem is that the previous character also goes to the final form, whereas the previous character should go to the initial form or medial form and should connect with the alternate final form of heh.
Please enlighten me on how to make this alternate final form usable.
Thank You,
Hatim