Depending on your team:
You can use new online conferencing tools to get together when you have things to show.
I always record meetings and make them available on a private, protected web site.
Whilst a share compensation scheme might help, advisors can be motivated by many other reasons. But a simple mechanism might be the old biblical honor & respect ... give honor to their contributions by inviting them to hands-on meetings/events, acknowledge their contributions in newsletters to staff/customers. Respect them for their time and give thanks for the time time they spend in thinking about a problem, even if you disagree on their solution. I'd point you to the concept of problemsourcing... where
“Problemsourcing is akin to crowdsourcing in reverse in that the openso openly acknowledge them as a valued in-house thinktank. Who knows, maybe you can dispense with the share scheme.
call initiator, not the crowd, holds the problem-solving capabilities,
and the crowd-members offer not solutions but promising problems that
would create substantial value if solved.”