I don't even think it is necessary that you include that. They do not need to know who owns the house or a letter of permission for you & your husband to live in your mom's house until you are settled on your own.
On the sponsor application there is a question that asks for your address and if you live with anyone. That is all they want to know or they would have asked for more.
Other things that could be joined are Dom Rep bank account and joint ownership of property or a house in the DR.
Immigration wants to see how your relationship has developed in the time you have been together, how you communicate, how much you know about each others life, finances, family and personal history. They want to see that your relationship is real and as normal as can be even though you are separated alot of the time.
Once your application is approved and your husband has landed at the airport and picks up his luggage you are free to live wherever you want....you just need to update your address with CIC.
When I was preparing our application, I over scrutinized everything. The best thing you can do is take breaks from your application or move on to another question. I know you want to answer everything right and do all the right things. Sometimes it helps to take a step back from that question for a day or two and then go back to it with a fresh take on it.
If you ask a few of the members who were successful in being approved quickly how they put everything together or what they wrote.....each one will have done it a different way...all of them the right way.
Some people answered the questions to the point and then submitted a letter from each spouse talking about the progression of their relationship and goals for the future. It is from the heart and honest.
Others answer each question with a long detailed explanation and then don't include anything extra except the pictures/phone bills etc.
We gave detailed answers and attached additional explanations to anything we felt was important to mention but not asked by any of the questions. We used a table of contents and included a cover letter explaining how we prepared the application and what proof we had included.
Just think of it like the biggest shool project you will put together and the subject is you and the love of your life!