With a POD at 1900, make a scenario where the Republicans successfully survive the civil war by escaping to a geographically defendable area, i.e. Spanish Morocco or the Balearic Islands.
Its kind of impossible as the Balerics, Canaries and Morocco were nationalist strongholds
Mmm, so Spanish Morocco as a Nationalist stronghold would work?
Perhaps a stalemate using 1937 lines where the front stabilized? No offensive to link up Madrid with Catalonia and less meddling aid from the USSR and aid from the UK?
Really you need to have the Aid that was being given get given out properly, the communists used the Aid as a cudgel and only really supplied units allied to themselves. A fair distribution of arms would have dearly helped the militias. Orwell played some armchair generalizing on how the front he was on in Catalunya could have been better managed into a victory.
As I said, no 'meddling' aid from USSR. Given only the pro-Stalinist communist party of spain was dicking with the aid. The libertarian communist POUM for example,was not that way. Maybe Trotsky stays in power in USSR and from that aid is evenly sent and the Trotsky led USSR is less willing to dick around with Anarchist groups (suppressing Krondstadt is one thing, but dicing around with those in other countries which is not a direct threat to USSR is another thing)
There was talk at the end of the SCW towards turning Llívia into a free territory of the Republic, which didn't work out as planned. It would, however, be interesting if that actually happened.
So basically... another Monaco? pretty sad ending for a nation that fought a war that brought many Socialists together