As long as it’s your children and a Gratuitous Transfer (no money changes hands), the contract shouldn’t lose the DVC-Y benefits, even if you take yourself off.
And FYI, it won’t create a new membership number if you stay on the contract and all your contracts have all the same owners at the end. IOW, if you add all your children to all of your contracts, and you remain an owner of all those contracts, no new membership.
But if you add one child to one contract and another child to a different contract, then new memberships will be created.