Hi,
Even without knowing what your more "custom" needs are, I suspect that it would be possible to create the addin that you want. But it could require a significant effort, so it is reasonable to expect that you will need to pay someone to do this for you.
I suggest that you contact your local JMP team who will be able to put you in contact with a partner organisation that could provide a customised addin.
If you would like to request that these capabilities are added to JMP as standard, then you can do this using the JMP Wish List.
Alternatively you might ask for help from the community as to how to use the existing addin and capabilities in JMP to achieve your objectives without creating a new addin.
Regards,
Phil