Edit commission / Commission variable over time

It would be useful to be able to edit already set partnership levels in terms of % commission. At the moment I do not see this possibility.

Furthermore, an interesting option (and even applicable for one of our partners) would be the possibility to set a variable commission depending on the duration of the contract.

E.g. an affiliate has a liftime commission from a referred customer, but in the first 6 months of the contract he has a 15% commission and in the remaining months he has a 10% commission.