Varun - what are your goals?
Do you want to plant roots in a better school district with better weather? Do you want to retire in 10 years off of passive income? Do you want to be worth $10M by the time you're 60?
Each of these goals require very different strategies (buying a Fremont/UnionCity SFH for #1, buying out of state income-flowing property for #2, buying a Menlo Park SFH for #3).
Folding a SFH into MFH will pay down the debt service faster through rental income but your equity won't appreciate as fast as a SFH in San Francisco, so it might net out. And then you'll be living in a 100 year old duplex and your wife is going to be asking you for a backyard for your kids and tell you to turn down the music when you're cooking dinner on Sunday night. I don't love this strategy, tbh, because it doesn't really spike on any single strategy (cash flow or equity).
Really think through your goals and build a strategy around it. For my wife and I, we are focused on retiring in 10 years so we can be full-time parents and volunteer. In order to accomplish that, we have a blended portfolio of an Oakland duplex that appreciates but doesn't cashflow, a SFH that appreciates (and wouldn't cashflow if we moved), and a low-income apartment complex in South Chicago that cashflows (15-25% cash on cash return if you do or don't factor in the debt service being paid down) that is unlikely to appreciate more than 1% YOY. We will likely acquire a new cash-flowing building every 1-3 years over the next decade and hope to retire off of the rental income while our stock portfolio grows until we are 50, then we will untap those until we are 60, then we will untap retirement accounts, etc.
I don't disagree with Paul, fwiw. I would not sell a SFH with that much equity in SF, especially since HELOCs and refi's are dirt cheap right now. If your goal is #1 or #3, just borrow cash for a down payment and don't sell.