The rules on alt interactions boil down to simply this. You may not use one alt to benefit another.
This includes using one alt to talk up another, to make them seem smarter or cooler or better in any way. To use them to provide support for, to do services for, to provide resources or aid to. To make them more sympathetic, to provide them with an enemy and so on.
You may use an alt to represent your character's employees if they have any, but their relationship must be purely professional. They must not believe their boss is an unusually good boss or their employee an unusually good employee or anything similar.