Linking two design variables with the dlink panel can be very tough if you have many design variables. You can only select them in the panel area and the names are cut off if they are too long. However if your design variables are all gage design variables then their names are simply the property names with a g infront of them. This allows you to select the design variables by their property. Since you can select properties visually it makes linking many design variables much easier.

You fist select the independent property, then the property that will have the same design values.

Limitation

You cannot link multiple dependent properties.

Functionality

Model/Analysis 

Subfunctionality

Optimization 

Interface

OptiStruct