InfoPath Dev

hey, i was wondering is it possible to auto number using (a,b,c ...etc) instead of (1,2,3 .. etc) maybe using "preceding-sibling" or similar codes ?

Yes!

Here's an xpath you can use: count(../preceding-sibling::my:group)+1

Replace my:group with the repeating group node above your field. Best practice is not to make the field repeating, but rather the parent group.

Good luck!