What is the proper procedure for fixing a split seam in the frame?

My car went into the wall hard enough to bend the front bumper support around backwards. I spent about 5 hrs on the frame machine making it look straight again. while straightening and from the incident some seams are split. I know for a fact that they are sometimes spot welded in spots and they use some sort of hard expanding glue stuff that is probably as strong as a weld to hold the seam together. Currently I have Hammered it back against eachother but over the winter months while the car is apart I am wondering if welding the split seams is a legal fix or not. If not what would you do to make sure it was fixed properly?

Stephen