I have a series of bent sheet metal plates each with a rolled edge flange on one side.

this is a 135 degree bend and is common to all parts.

almost every time I open this part or use it in an assembly the flange looses it reference to the line/surface and causes an error.

I tried other things to make this edge a reference like adding an axis for it to hook to so that it wouldn't change. That didn't work.

Can someone tell me how to get this feature to stay put. All it is asking me for is the referenced line and when I select it is ok.

I don't want to have to deal with this more than one more time.

thanx