Hi,
Re-sync will not work. You will need to re-initialize from C to B.
As I understand your plan:
1st : A(PROD) ---------> B (DR) [Both A & B will have common-snapshot for their respective relationship, hence sync & re-sync is possible]
2nd : A(PROD) --------> C (pre-PROD) [Both A & C will have common-snapshot for their respective relationship, hence sync & re-sync is possible]
3rd : C(PROD) --------> B (DR) [No, There is no-common-snapshot between C & B to perform resync/sync] = re-initialize will be needed.
Thanks!