Information about Form 8958 in a Community Property State

Hello:

I recently got married a few months ago at the beginning of September, we both lived in Idaho (a community property state) . My questions are as follows:
1. Do we (my wife and I) have to bother with filing form 8958 when doing our 2020 if we were only married for the last 3rd of the year?
2. If the answer to the above question is yes, We would both like to file our taxes separately so when completing form 8958 do we HAVE to split everything in half (income, withholdings, etc.) or can we just fill in the form but allocate all of my wife's income and withholdings to her and vice versa?
3. If we are not able to allocate each of our income and withholdings accordingly and we have to split everything in half then why have the option to file married but separately? why not make it so that folks just file jointly if everything will still come out to half?

 

Thank-you