What do you do when two snails have a fight?
Leave them to slug it out!
Interesting Fact: Sometimes creepers build nests in unusual places, such as behind window shutters, in or under roofs, inside fenceposts, or inside concrete blocks. One brought up a family in a specially constructed box made of pieces of Douglas-fir bark. ( https://www.allaboutbirds.org/guide/Brown_Creeper/lifehistory )