I sent a child off to JK this year age 4 that still has a two hour nap every afternoon with a soother and a stuffed bunny that he screams for if he doesn't have. The soother was in his mouth all day lest he scream and I just got tired of it but made him take it out of his mouth if he wanted to talk to me. Feeling sorry for his teacher in the full day jk school program. I tried, I really did but gave up because the child would whine to parents about how sad he was at daycare because I took it away. So not risking losing the child and the parents and child will learn soon enough they should have listened to me over 2 years ago.
In the case of swallowing only other option I could see is using a piece of ribbon like the clip on holders but sew the soother to the ribbon instead of snapping so it stays put but for sure child needs a different size.
Considering my experience above I totally support the get them off the soother at your house as soon as you can even if it means a week of restless naps, etc. The child will be better off and safer down the road.