While I understand the overall idea here, I think this particular way may be cause of a lot of potentially worse issues showing up. The biggest problem here being, what would stop 30 or 40 players from basically creating one massive alliance that no one can even hope of standing up against? The idea pretty much makes it so that we end up eliminating alliance size limitations.
I think the overall idea is to have a connected sub-alliance feel to the main alliance. I think it'd be best to make it so a subs would provide and be provided radar coverage with it's main. Essentially, main and subs can see all the same things. But for this added bonus, I'd say, resource OPs should be shared among all alliances equally. So instead of everyone gaining +x amount of resources, each resource OP provides +x and then is divided by the total amount of players and distributed equally. This would mean that the more subs you have, the more your team suffers resource wise. Along with this, if the sub (or main) decide to break off, when they break it, obviously the benefits (radar coverage) would disappear immediately (and also tip off if a betrayal is coming).
If you allow the subs and main alliances to help in wars however, it'll just create too big of powerhouses. Get enough players in your team, and what would stop you from stacking every unit in 1 OP and then just using the abundance of players to ion every nuke that goes for them?