i think you should carry him as much as he needs. it won't make him feel more secure to not have his needs attended to.
but your dd deserves to be carried and be secure, too.
can you try two unpadded ring sling, in the twin cross-carry?
two mei-tais, rather than a mei-tai and ergo?
maybe put on the sling, then put on the mei-tai, put a baby on your back and a baby on your front.
i don't envy you this, it sounds tough.
you need to contact a mothers of multiples group to get more ideas!
but your dd deserves to be carried and be secure, too.
can you try two unpadded ring sling, in the twin cross-carry?
two mei-tais, rather than a mei-tai and ergo?
maybe put on the sling, then put on the mei-tai, put a baby on your back and a baby on your front.
i don't envy you this, it sounds tough.
you need to contact a mothers of multiples group to get more ideas!