As I said, California regarding a prenup does not require the prenup to be drafted by an attorney. It is a contract that any party over age of 18 can do it him or herself. The requirement is that either both parties represented by counsels or expressly waive the rights. If one party is represented by a counsel, the other party must be advised to seek counsel representation.
If the prenup includes spousal support, then the party against whom the prenup enforcement will be sought must be represented by counsel.
Again, there is no requirement a prenup must be drafted by lawyers.
In your situation, it is a postnup so those requirements regarding counsel may not even be applied. I do recommend a counsel representation though since in your situation, not only a you need a postnup but essentially you will have to recharacterize the real property such that it is likely you will convert a community property to a separate property or vice versa through transmutation before you can even think about a postnup.
You will need two independent attorneys to represent you and your spouse.
