I assume this setup would use offline signing, in which case different seeds don't increase security.
Still a central point of failure, where one seed gives you more control than it should and the compromise of a single seed equals to a compromise of 3 entities and only requiring the participation of one more. Nevertheless, that is not the point as security of seeds isn't the central discussion here.
You don't need to use different derivation paths, you can simply use different addresses/keys from within one Electrum wallet for A1, A2 and A3.
That is only if you want to use a single Multisig address without an easy way of avoiding address re-use. So yes, it can work in that case.
Generally, if you want to create a multisig system with HD seeds, then you should use multiple seeds instead of different derivation paths.