"we hope to make it so that the museum is part of the RPSI, and not vice versa.
But at the present, the funders are insisting that the branding should be museum-related."
Who are the funders?
Are they saying that they have got a bequest conditional that the Museum takes brand precedence?
If this is the case, what are they waiting on to negate this?
The RPSI Donations FAQ reads:
Wherever possible we will respect and act upon your wishes, providing what you have requested is still possible and does not conflict with Society policy.
.. Ultimately, if what you request is too restrictive, it may be necessary to turn down the bequest.
The current Branding arrangement seems to override that a tad.