If your combination sofa keeps moving around, you can use the Modular Combined Sofa Connector: the connector to hold the sections together.

Features:

Durable and sturdy material.
Compact and easy to carry.
Easy to install.
It is a perfect sectional furniture connector.
Perfect to secure the sofa, couch, and other furniture.

Specification:
Material: Plastic, Metal
Color: As shown
Size: About 13.5cm
Thickness: About 2mm

Package Included: 
1pc x Sofa Connector