I am currently using fmriprep for preprocessing and then performing 1st/2nd/+ level analyses with FSL Feat. I am aware of this post which offers a useful solution for resolving the issue that feat will not perform the 2nd level analyses without a reg folder. However, would it be possible to circumvent the extra step of running a full analysis at the first level and use equivalent registration images output by fmriprep? In other words, could I “build” and equivalent reg folder from the output generated from fmriprep that feat would recognize? For example, would it be possible to rename files in a way that feat would recognize them? This may not be possible but it would be useful to get confirmation from more experienced neuroimagers. Thanks in advance!