Two Companies with joint ownership of software product

Looking for ideas on how two companies can have joint ownership of a software product that both developed together where we can keep costs, liabilities separate. My thoughts 1.) Both companies own some percentage in the product (50/50) 2.) One company will likely have to “administer” the product so maybe a cost/fee should be subtracted from the 50/50. 3.) Liability should be split 50/50 between 2 companies. 4.) Functionality already developed could be created as the “core” product. New functionality could be created by either company and it would be considered an “ADD-ON”. The company that provided the ADD-ON would get most if not all of the percentage of license fees associated with that ADD-ON. The CORE functionality would be split 50/50 (after fee). 5.) Both companies would market the software independently. Whomever “closes” the deal would be entitled to some time of percentage of the sale. (The rest split between the CORE and ADD-ON company interests)