Hello from Saudi and asking help on my app for Sports Activities booking

Hello from Saudi
Thank you team for Glide!!! It is an amazing platform and I have learned a lot from your community…

I am working on a fun little project for booking sports activities for a small community

Lots of work is needed on the interface and making the app looks better but I am trying to figure out the flow first,
Currently I am struggling with the concept of adding multiple friends (friends are user labeled as “Favorited”) to a booking while making sure that the second friend is not redundant.

Below is a screen shot of the problem:
(I shouldn’t be able to add Lebron twice)

Also I have attached a copy of the sheet for your information:


Hopefully this would help.

Thanks @ThinhDinh for the assist,

However, the solution was not applicable for this case, but it gave me an idea to partially solve it:


There is couple more problems mainly when a new users is created the sorting in the booking details changes and the tick mark changes with it, also the solution may create unnecessary rows (Problems can be solved with some scripts),

The other problem is navigation after the last screen (choice of friends) I want to go back to the home page or remove the “< back” button (any ideas?)

PS: Template is now open to copy