Sequence Configuration has a obs-focus with a cardinality of 2..2. I assume this for the case when trans is value. But if the value is cis, then the cardinality could be 2..*

Not sure how, but It would be nice to be able to do this. Then I could effectively have a set of sequences in a phase-set.

Practically speaking, I think most labs report if they have evidence of sequences being cis, but not for trans. Evidence for trans is usually inferred from lack of evidence them being in cis.