if you are joining on the fields then it is not needed in any formula as it is redundant to the join...and the {F0101.ABALPH} will be based on that join.
I still do not understand your set up, just pointing out that you cannot really handle condtional joins in the select expert or a crystal formula. these options do not change your data.
If you are having a join issue because of data type mismatch you can handle that in a command by converting from the type in one table and joining that way.