It is permissible to work in debt collection in return for a fixed fee or a percentage of the debt recovered, because this comes under the heading of acting as an agent in return for payment. But it is stipulated that the debt should not be Riba-based.

It is not permissible for a partner or proxy to buy something from himself, except with the permission of his partner or the one who appointed him as his proxy. If your partners give you permission to do that, and they are adults of sound mind, then there is nothing wrong with it in that case.