I am PI of a research group and in different projects regarding sample analyses, it looks like we will be able to license 4 patents to 4 different companies. I can tell you this success was not neither expected nor planned. And now the problems come; the money we receive from each patent, how to distribute it among the different participants. In order to avoid problems, I decided to distribute it equally between the number of people involved on each patent, which varies from 5 to 7, including me. 

But some people are disappointed because they consider that other people did much less and should receive less percentage. In addition, I do not like this completely since I got all the funding for the projects, infrastructures and negotiate it hard with the companies, so I think I should deserve it a bit more, but I know that with this I will have problems in the group. Of course, I should have written everything down, the regulations, before starting the projects, but now it is too late. In order to solve this I thought about preparing a document, in which everybody writes down what they think they did, and how that part contributed to the invention. Then I think we could start a reasonable discussion, so people that did less, could not say the opposite, and finally we would reach an agreement. Another solution I thought would be to leave my University to decide on this. 

My questions here is, how would you solve this problem, and if you think (and why) that a PI should get more part of the contribution.