Not familar with this problem, and I do have a mother in law!
I suggest due to the safety nature of the seat belt, take it to your local GM dealership the next time this happens.
Insurance companies can be very picky in the event someone is injured due to an unlicensed person messing with the belt assemblies!
2007 LS wagon 2.2 Automatic Imperial Blue Metallic
Winner - April 2014 Featured HHR of the month
Winner - April 2015 Featured HHR of the month
Winner - April 2016 Featured HHR of the month
Co-Winner - HHR of the Year 2015
Always Keep it clean and drive it often, and take a kid to a car show and start their passion for cars!!!!