Nancy,
Here is what we did with Sign Inventory. There are up to 4 signs in each sign poles in our case. So, we created one point feature class of poles. The Pole ID is the unique ID. There are attributes of Sign1,Sign2,Sign3, and Sign4 in one feature class. This worked good for the collection. We have not split the sign feature class yet, but you can split the sign feature class into 4 feature classes per sign after collection. All 4 feature classes will have the same Pole ID. So, you can join them in the future if necessary.
With your existing data, you might want to have all signs in one feature class by joining multiple times. After having one feature class with all signs, then proceed with what I mentioned above.