When you merge 2 patients, common relationships are duplicated. For example:
Patient 1: Has Child 123 and Parent 456
Patient 2: Has Child 789 and Parent 456
If Patient 1 is merged into Patient 2, you get:
Patient 1: Voided
Patient 2: Has: Child 123, Child 798, Parent 456, Parent 456. The system should recognize that the same relationship should not be added twice.
In general, you should not be able to add duplicate relationships to a person, regardless of whether it is through the merge patient screens or elsewhere. This should be checked in the API / Services.
Also, the notPreferred's relationships should be voided (and they currently are left behind). It would be best to leave a rabbit trail in the void reason.