How can I cycle through range, and extract text from rows, if rows contain specific text?

Hello, community,

I've run into this problem today and I am hoping you guys can point me in the right direction. Example sheet attached.

I have a list of services in a range, some of which contain sub-services within the same row, written in this format: "Main Service: Sub service".

I have managed to extract the main services out of this specific range through formulas. However, I would like to create a list (with comma delimiters) for each main service, containing every one of its sub-services. So I would basically have to cycle through the initial range that contains both (like "Main Service: Sub service") and check the already extracted main services, one by one, whether a specific row contains it, and then extract the sub-service and add it to a list.

However, some of the services also have this format "Main Service: Sub service: Random Info". I need to make sure that the ": Random Info" part does not get extracted, so I will basically have to check each possible extraction whether or not it contains a ":" character and then delete everything to the right of it. Totally doable for me, if it weren't for the already messy array formula I am expecting to be needed here.

If this isn't clear at all, I've included two examples within the example sheet as well, detailing what exactly I'm looking to extract and how.

I truly hope you awesome people could help me out, or at least point me in the right direction. I know for a fact I need all the help I can get

This is precisely why I love this forum! Worked like a charm. Thank you! Rep added.

I do have a follow-up question. If I remove the ": Durlu" from the first "Discovery Session" main service, leaving just the main service in place, the formula stops pulling the "Discovery Research" underneath from the second entry. It basically seems to ignore sub-services in case it finds main services that contain both types of data (one with sub-service included, and one without). Do you have any idea if a workaround is possible?