trying the remux new subtitle track for the first time, followed the guide up to a point were im not sure what to input. in your example you set first mpls 3 first m2ts 3.
if the playlist is
00001.mpls and the corresponting m2ts is
00037.m2ts then i take it i set it it to
first mpls 1 first m2ts 37?
edit - should have read above