I am learning Perek Alot haShachar in Masechet Brachot, and the issue of tashlumin made me think of the following question: Is there such thing as tashlumin for ne’ilah on Yom Kippur? I can’t find anything on this. Thanks.

Shalom. I'm glad to see that your learning is enriching you, and bringing you to greater and greater levels of questions and striving in understanding. In reference to your question - yes this subject is discussed. Here are some sources to help you further your learning in this area:- (from Tefillah KeHilchatah, Rav Fooks, 23,79) see Shevet Halevi 4,13, Or LeZion p99. Chachmat Shlomo 623,1. May your learning be a blessing. D. Sperling.