multiple annotations into one event

I have a Brainvision data that for each 3 condition have four annotation markers. How can I combine these 4 annotations and categorize as one condition, then be able to compare these 3 conditions? I have a lot of annotation markers (almost 90) however I will only check these 3 events and I need to group the annotations as a condition. For example Stimulus/S 2, 4, 22,90 = one condition, Stimulus S 4,70,64,33= one condition etc.
Thank you

Hello @irmakoz, and welcome to the forum!

I suppose the merge_events() function can be of help here, have you checked it out already?

Best wishes