Combining 1031 exchange and a section 121 exclusion

[Geoffrey You]

Hi all, 

Hope y'all are doing well in this crazy market! I was hoping y'all can help me answer some questions with my complicated situation. 

I am currently in the midst of selling three of my rental properties in Greenville, NC. I would like the proceeds of those properties (via 1031 exchange) to be used as a down payment for a hybrid residential-commercial property that I am looking to purchase in NYC. This replacement property has 3 residential units and 1 commercial unit on the main floor.

My mother is also looking to sell her primary home in NYC and is interested in using her profit to do a section 121 exclusion towards the same property.

Essentially, we are hoping to put both of our names on the replacement property. I am hoping that the profit from selling my rental properties (1031 exchange) together with the profit from selling my mother's primary home (section 121) can be used as down payment for the replacement property. My mother would then move into one of those 3 residential units. 

Is this a feasible plan? Any advice would be greatly appreciated!

Geoff