Grouping close AI and Assigning same time

Hello,

I spawned in a bound box a number of AI and they move using Spline and Timeline based on random departure delays and it works.

Now if I need to detect from 2 to 10 AI that are close to each others based on max distance and assign the same random delay to them so the group move together on the Spline , is there a blueprint or tutorial close to this use case I can refer to?

Thanks