Oh..!!!

I just forgot about backspace button..!!! It helped.

But, there is bug..

When you close conversation and again reopen the same, it will show you last unfinished message. On pressing "To" shows only last contact selected. I am not able to select other contact here.

Either I have to clear the contact by backspace and then only "To" will show all contacts which you can select.

or

I have to first select last contact then press "Done" and again pressing "TO" will show you all contacts..then only you can select newer one and deselect previous one.

I think this is bug. In first place itself on pressing TO you should get entire contact list...best is discarding entire unfinished message if you close messaging application. (any how it does not take much time to retype the same )