I have $800k in equity right now but I have bad credit in my current situation.

I do a mix of these along with cosmetic flips and flips that basically just need to be cleaned where we bought low with a ton of built in equity. 

The combined value of the three rentals is $1,500,000, with remaining mortgages totaling $290,000 (with 12 years left), leaving me with $1,210,000 in equity.

What may be $60,000 in equity to you could only be $15,000 harvestable.I never let my cost of capital rise above 7% when doing cashout refi. 

. $900k, which would be almost $350k in equity today with $250k all-in for down payment/closing/rehab.

We'll both chip in equally for the costs and expenses of the acquiring the property (looking to buy an apartment with a value between 500k-600k in Chicago) and live together for a few years in it.

Or should I not even wait for that (eg the opportunity cost of my $200K now in equity could be spent elsewhere)?

I probably have almost 3 million in equity now with them.

What is the best way to go about pulling from the $100k in equity in the first property for a down payment on the next property?

With our growing family and careers, the part of the plan we didn't act on, was acquiring a new investment property every few years.Currently the duplex is cash flowing about $1200 per month and it has approx $225k in equity.