I have a list of around 4 thousand people. Each person belongs to one "Group"
which is tagged with a number.

Basically there are two columns one showing the name and one with the group
tag. What i want to do is have the group tags showing all the people who
belong to that group.

So I need to merge the data from a number of cells into one cell without
losing the data. Any ideas?

Thanks for your help.