If you're using the Spooky Remote transmitter, you should be able to use five or six specimens as long as you make sure that each one is small, i.e. cut each fingernail into three or four segments and use just one segment from each subject - remember, DNA is microscopic, so even the tiniest sliver is sufficient.
With a home-mde DNA Holder, up to 20 different DNA samples can be inserted. But cut each fingernail in three and only use one part for each subject. Wrap each part separately in paper masking tape, write each subject’s initials on the tape, and insert them carefully between the two metal or foil strips.
Then place the frequency generator (or a book/glass ashtray) on top of the DNA Holder to provide a weight so that the two strips are pushed as close together as possible.