Aspects of the relationship:

Serials A and B merge to form serial C which has a new title

Linking entry fields:

CONSER practice:

Serial A: 580 field and two or more linking fields (785 17) for the title(s) it merged with and the new title; serial B: same; serial C: 580 and two or more linking fields (780 14) for the earlier titles

Non-CONSER:

Serial A: 2 or more linking fields (785 07) for the title it merged with and the new title; serial B: same; serial C: 2 or more linking fields (780 04) for the earlier titles

See also:

14.2. Chronological relationships (fields 780/785)