How to link/separate tags in a category

Hi

We have categories set up in this fashion.

Category:

1

1a

1b

1c

2

2a

2b

2c

These are NOT parent and child

We have about 15 tags we use to separate various entry types.

t1

t2

t3

t4

we would like to put links on a page that would only link to a tag in 1 category at a time.

Possible?

ty