Merging Multiple (pgn) Games of an Opening into One Game (File)

Hello,

I want to merge multiple (pgn) games of the same opening into one game, so the sidelines branch off where they occur, for further analysis. I do not have chessbase.

I have learned how to do multiple searches in SCID to narrow down my results. Unfortunately, there is no way to highlight multiple games in the GameList Window and merge the games that way. It seems like there might be a way to do them one by one, but I do not possess whatever skill/knowledge to do so. Therefore, I tried creating an Opening Report and click on the Merge Button provided, but I just get error messages, and no results.

Furthermore, when I import multiple games from one pgn into a study, they automatically split off into separate chapters.

Is there a free and painless way to achieve my goal of merging multiple games into a single pgn file, with the sidelines branching off into their own variation(s)?

Thanks.