There is a new product on the market to connect batting pieces together. It is called "Heat Press Batting Together"
and is probably available at your LQS. If not available there you can go to this website:
www.heatpressbattingtogether.com
I have used this to piece batting together for larger items like quilts and also for table toppers and runners and placemats and have been very satisfied with the results.
Judy in CO