Hi Angie, and welcome
A picture of the area would be really helpful. Also if you could complete your personal profile with your location (city, zone etc.) that really helps with answering questions, too.
If the lilies are just barely poking out of the ground, you probably could move or thin them if you're quite careful. But this is certainly not the best time to do it and it could compromise their bloom or set them back for next year. After they bloom, when the foliage is starting to fade is most likely the best time.
But first we need to have a look at a picture to see what you're dealing with. If the lilies grew 4ft tall last year, and if the stems were cut off at the top that would indicate they grew pretty well and bloomed last year. It would be a shame to miss out on those lovely blooms this year if you don't have to.