Should I book Moscow–Abu Dhabi flights as one connecting ticket or two separate one-way tickets, and what about baggage on codeshare flights?

Booking two separate one-way tickets for Moscow–Abu Dhabi and back is fine — baggage and check-in are processed separately per leg anyway, even with a single combined ticket. It's odd that two separate tickets can come out cheaper than one combined fare, so double-check the fare rules before buying.

Booking through an aggregator like trip.com for a Moscow–Abu Dhabi flight raises reliability concerns when both legs are effectively separate tickets, but in practice check-in and baggage drop work the same as with a single combined ticket.

On the return leg Abu Dhabi–Moscow with an Aeroflot single ticket, adding paid baggage online sometimes fails (while it works fine for the Moscow–Abu Dhabi leg) — this looks like a booking system glitch, so try adding baggage again later or contact the airline directly.

Etihad doesn't offer a direct Dubai–Moscow flight: the airline's own website only shows a routing via a connection in Abu Dhabi (Dubai–Abu Dhabi–Moscow, and back Moscow–Abu Dhabi–Dubai). This connection option usually only shows up when booking directly on Etihad's site, not through aggregators.