People often ask me why there are multiple signs for one concept.
But that also occurs in spoken languages! That's a part of languages.
It might be difficult for parents to learn all of those different signs, but that's because of our limited memory.
Recollection plays an important part in language acquisition.
There are different strategies for handling that.
If you don't know a sign while having a conversation, you could ask others what that sign means, for example.
You can learn all the different signs by talking about that concept with others.
So it's not really a communicative obstruction, but rather an important aspect of it. Variation in language is very common.
A different country asked us to help standardizing their sign language, for example.
We told them no, but we did want to help record the sign language.
When to use certain signs is a cultural decision.
Sign variation should be protected. The community can decide for itself which signs they use.
England has seventeen different signs for purple, for example. That's just a part of their culture.