Is this considered back-to-back ticketing and would I have problems when all flights are credited to M+ ?

Ticket 1: JAX-IAD-ZRH
Ticket 2: ZRH-SIN
Ticket 3: SIN-SFO-JAX
Ticket 3: JAX-SFO-SIN
Ticket 2: SIN-ZRH
Ticket 1: ZRH-IAD-JAX

ZRH-SIN would be on SQ, the rest on UA