What steps should be taken to transfer the deed to my Mom's rental property to my sibling, living in that property, AND still collect rent?

I agree with Igloo, you must contact a real estate attorney about this. How about just adding the siblings name to the current deed? Then your mother still owns it and the siblings name is on there? Why does your mother even want to do this if she intends to divide among all of you? Not sure that would be so easy to do if one siblings name is on the deed after your mother passes. This is a serious legal question and I would not make a move without locating one. If you need an attorney and have no funds, contact your local Area on Aging and see if they have a list of some attorneys that will help pro-bono.
Blessings, Bridget

This is best done by an attorney who practices in the county where the property is located. If you haven't done other legal with your mom, then get all done then 2.

A lot of this really truly dependents on what you and your 3 siblings feel about the house, the sibling with co-dependency issues and IF mom really needs the money.
Where is she living if your sibling is living in her house?

It sounds like your mom wants to "sell" but still control, this is kinda hard to do. Either your sib has a deed of trust and owns the house or not. A real estate attorney can structure the act of sale to deal with a default.

What I'd be worried about is if say 8 years from now, mom is 90 and needs to go into a NH. She has outlived her assets and qualifies for Medicaid. All is nice and kum-ba-ya, she is in a place that provides what she needs. You and your sibs are all 8 years older and things change over that time. Then your sibling defaults on the property and presto..surprise...the property is now back in your mom's name. This is not a homesteaded exempt property under Medicaid - it is a total asset and must be sold in order for her to stay on Medicaid. The NH sends you a letter stating she is now private pay and they need 2 mos. in full for her to stay. You end up doing a quick sale and perhaps even a undervalue sale to get it all done and over with. Real estate could be back to the go-go years of 2000-2005 then (LMAO). All the proceeds from the sale must now go for her care and you cannot be reimbursed for the 2 mos you paid in full without more issues with Medicaid.
So really think about the long term in all this. Good Luck.