I am the office manager in Kalkaska and had a gentleman stopped in the other day asking for a contact number for a Maple Syrup expert. I have looked through the topics and find an expert, and just don't see anything or anyone specific. He is specifically wondering if Basswoods are beneficial to the production of his maples or if they are detrimental? He stated that he has been told and can't find an answer.
Kalkaska County Michigan trees and shrubs
I have not heard anything detrimental about basswood growing in a sugarbush other than the fact that the trees could end up competing with sugar maple for sunlight and space. Here is a Forest Service guide to sugarbush management in the US and Canada, and while basswood is mentioned several times, there are no warnings about it being found side by side with maple.
If you'd like, you can refer the landowner directly to me as I'm located in Roscommon County. I don't specialize in sugarbush management, but have a bit of experience with it and would be happy to put the landowner in touch with someone more qualified if necessary.