Yes, you can "split" the time. My cat had to do just that when I brought her over with me. There was a mix-up at my vet's office (they were clueless about DEFRA regulations and I was pretty naive too) which resulted in her needing a second blood test.

That messed up my timeline so when she arrived in the UK her 6 months was not yet up so she had to spend some time in the quarantine kennels in Binfield. (Great facility, really nice people)
Once her 6 months total was up, she was cleared for release and came home with me!
It's not ideal but sometimes we don't have choices. It's definitely better than your furkids spending the entire 6 months in quarantine.
