My redfoots are too young to breed, but from everything I heard
and read you should not breed Cherryheads with 'normal' Redfoots.
The breeder I got my two hatchlings from breeds both, Redfoots
and Cherryheads, but definitely keeps them separate.
From what I read, 7" would be borderline small, but other people
might be better able to answer that question. The danger would
be, that eggs could be produced, but the tort would not be able
to pass them. A member of my Redfoot group had to break the eggs
of her female, when she tried unsuccessfully, to pass them.
Otherwise you could run into the problems linked to egg retention.
To recognize a gravid female, she will start 'pacing', which
means walk and sniff, to find an appropriate laying site.
This site should have between about 1 - 1.5' of medium consisting
of sand and soil (to make digging easy, but firm enough to keep
the hole shape), slightly moist, with temperatures at laying
depth, that correspond to the incubation temperature of the
species (between 28 - 31 degrees Celsius). This can be achieved
by placing a heat lamp above. Some females prefer a nest box for
privacy. Outdoors nesting sites on slopes are preferred.
Hope that helps, but I think, you should not continue keeping
them together,
Gaby