Trying to filter out duplicates when counting

Hi Everyone, I'm trying to make a fairly straightforward game. I plan to separate a bunch of people into 8 different groups. I will give each group 5 minutes to write down a list of things they need to bring with them on an upcoming trip. After the 5 minutes are up, I will ask them to read out loud what they wrote down for their packing list. Whoever has the highest number of unique items wins.

As they read them out loud, I will be typing them into the spreadsheet I've attached to this post. Here's where it gets tricky - I don't know how to have each group's "unique total" number equal the amount of unique items in their packing list. I need it to compare what I've typed into a "Packing List" column against all of the other columns to check for the same item in other columns. If it's in 1 other column, the count would be "2" indicating 2 groups mentioned it. If it's in 2 other columns, the count would be 3 indicating 2 other groups mentioned it.

- For the first group, the count for each item would be 1 (because no other group mentioned that item... yet) and the unique total would simply be the total of all the 1's in that group's "Count" column.
- For the second group, the count for each item would be 1 unless another group already listed that same item. If another group did list that same item, the count would be 2 (indicating another group mentioned it) and the cells would ideally be highlighted in red to indicate that it was a mentioned more than once.
- The same logic would follow for each of the additional groups.

I've manually entered numbers in a couple of the "Count" columns and changed some of them to red as an example to illustrate what I'm trying to automate.

If anyone could help me enter the appropriate formulas into my spreadsheet, I would sincerely appreciate it!

Thanks so much! This is exactly what I needed.

I've marked the thread as solved and attached the final and working version for anyone else who many need this.