There is a good guide on this by Josh Hill that will point you in the right direction:
I don't think it addresses your requirements around routing channel partner leads separately, but I believe that would be best managed as part of a central operational routing/lifecycle program rather than within a marketing program.
I have seen this work well using a tokenized Marketo LP and then individual programs for each event that listen to data values changing after people fill out the form on the signup LP in order to register people.
This still takes work but is quite reasonable to manage - clone one of the individual event programs, update some tokens on the central signup LP, and you're good to go.
If you post exactly how you've set it up now I can offer some more constructive suggestions.
We do biweekly demos and just set them up as separate (non-recurring) GoToWebinar events with corresponding Marketo programs. I tokenize the **** out of the program so it's not too much work to clone all the programs. I do like the Marketing Rock Star Guide setup.
I wonder if for your partner leads you could use Workspaces. I learned about these at a recent Marketo User Group. It was recommended as a way to segregate leads. Another way would be to give them tracking URLs to a central signup landing page that lists all the webinar dates, then they click on the date that works best for them. Then you only need one tracking URL.