Excel formula to combine text in column

Hey Excel Forum,

I need assistance with a spreadsheet and was hoping one of you excel geniuses can help with a formula. Ive attached an example spreadsheet to this post.

I need to combine all data within a column (Y) and have it separated by a delimiter (?).

The only issue is that it needs to correspond to a specific product found in the first row of every new line item. Some products more line items then others. I attempted to use the TEXTJOIN function, but it only works for a certain range and I need the function to recognize a new line.

Please view the spreadsheet for better clarification. I provided two examples in column AA.

I need a function that I can apply to a spreadsheet with thousands of entrys.

Hope that makes since. Thank you in advance.

Give an example of what you did in the lines you combined. what was the criteria and which lines did you join together??