Sharing tables between 2 plugins.

I have a client using the "Connections Membership Directory" and the "WP-Invoice" plugin. Both are non WPMUDEV plugins. The 2 plugins both have their own database and some of the data such as name and address are duplicated across tables. Therefore if member information is updated it has to be done in 2 places. Is it possible and feasible to someway link the applicable fields in both tables so if one is updated manually the change would apply to the other one automatically? If so how would one attempt to do this?

Thanks,
Larry