enable more comments for 1 account

Hi experts,

we need to add something like an "analytical" accounts for each account in our account dimension.

The problem with comment is that for one account, we can store only one comment.

We thought to add an additional dimension with some predefined members, but then users will lose a flexibility to add a comment that they wish.

example:

account  comment1

Travel     2 person travel to Sydney

Travel     3 person travel to Tokyo

any idea appreciated in advance,

thanks