Sub contracting Environmental Design Fees

I am working as a designer for very high end clients in fashion and cosmetics (couldn’t get much bigger). However I work with a PR Event producer that has all
the clients- I bill them directly. I never get to see what the budgets are, and have been severely undercharging for my services which consist of the total design idea, layout, custom furniture, materials specs, management, supervision etc. I know the PR firm probably bills at least 5 times the amount I’ve been billing…
Is there a fee standard when designing as a subcontractor? Or at least some ideas of what to charge? Any one help?

Find the value…how much is it worth to them.

Or bill for your design services sepporatly from the fabrication costs

Difficult to know how much it’s worth, but I estimate some of the budgets to be between 50k - 100k

you have experiance with them now right?

so you know ho much you have been over in the past, now try to incorporate all the extra time and expenses that you left out in the previous jobs into the proposal for the next. Also detail out each process and step. Then it is easier for you to say “wait a minate this is out of scope, and I will have to ammend the contract if you want this to be included.” Always define your roles and the roles of the client. you can never be to specific in a buisness deal.