New Beginnings

I was in a relationship with a man for 9years. In this relationship we had a son together, and I had 3 other children from a previous relationship. We felt the need to call it quit 3 years ago, and shortly thereafter he started to date another woman. Their relationship was fine-with the exception that he still was in love with me as well, and felt disloyal to his son for not being there everyday at times, We both missed each other, and would see each other again til he finally would come back to me. Then, because he still had love in his heart for her...and she for him as well, he would slip and see her til I as she did, would find out...and leave him again, then he would go back to her.  A year ago they had a daughter together(she also has 2 kids from a prior marriage) and the relationship continued to grow but the cycle seemed it would continue. She and I have talked several times as of late, and its apparent he loves us both .Its apparent He doesn't like hurting either of us(giving the way he tries hard to hide his feelings for the other one.), and wants to be a part of our childrens lives, but when forced to make a decision to choose one of us..he.always misses the one he passed over. She and I decided we didnt want to have the lies or deceit continue, when it was not a some type of weird game he was playing...he just genuinly loves two women. So we both agree (per her suggestion) that we want to attempt a plural marriage. One that allows for acceptance of each other, and instead of competing for him, we share our love for him, and allow him to love us both freely. That actually will give us more of a secure and trusting feeling by knowing he's seeing the other one, because we are apart of it as well, plus it would be done on our terms. We have to the best of our ability weighed the obvious pros and cons, but feel the pros definately out weigh the cons. We want to ease into it- try and find a joint home big enough for our 7 children total, but in the mean time he could go between our homes. Because of my position and longer years invested we both agree I would be the "legit" wife, and she the spiritual. Also we want a spiritual ceremony, for she and I as well to dedicate ourselves to each other, accepting our new sister wife, and her kids as our own. By the time we told him what we really wanted to do today, we layed it all out for him and he was in shock-A little nervous at first we were putting him through some sort of rogue "man test", or a trap of some sort, lol. Then apprehensive that we could learn or at least try to get along without jealousy or competition, but seeing how sincere our intentions are, and the desire to try he has agreed for the sake of us. Our only problem it is, none of us were raised nor are personally familiar with how a plural marriage "format" actually works. For lack of a better term, we'd be "winging" it. Please...if anyone out there could give us suggestions it would be greatly appreciated! For example...how is time usually divided? Is it done by the day (she get 3 days, I get 3 days) or is it week by week? We really need something to base this on  Thanks to you all!