No it is OK.
If you have anatomicals from these subjects but from different scan sessions, you can align the EPI (assuming they cover a decent chunk of the brain) to the anatomicals from a different session. 3dAllineate would do this registration.
Alternately, you can take those EPI directly to TLRC space with @auto_tlrc and use the average EPI template. Of course. it would be best if all your data from the same study are aligned to tlrc in the same manner.
Note that we are improving a set of tools to better align EPI to T1 (whole head). So if you have trouble with the alignment, send us the data.
cheers,
ziad