We had to replace a part on our sand filter this past season due to the filter dumping sand in the pool. Our problem wasn't the laterals but the part that they screw into. The crack was so tiny yet allowed about a 1/8 cup of sand into our pool each day. I personally would replace the lateral because having sand dumped into our pool drove me crazy. The filter that was supposed to clean the pool actually was the thing making our pool dirty.

If you have to keep that lateral then I would go to a hardware/auto store and get a plastic repair kit. My husband uses them to fix cracked plastic on his motorcycle. Not sure how it holds up underwater though. The screen idea might work but it would have to be a really fine screen, the sand particles are so small.

The sand in your pool won't hurt it and it you don't mind vacuuming everyday you could leave the broken lateral and change it out in the off season...that is what we did.