and dump the rest into a brokerage account which holds ETF's invested in essentially total stock market indexes (VTI, VOO etc.).

Investment Info:Small multi-family (2-4 units) buy & hold investment.

I'm struggling to find a good deal sheet calculator that I can use with my hard money lender. I have found many websites, but they are for fix and flix situations or a calc sheet to get approved/join their lending ser...

If you parents own the house until death, the property will get a stepped up basis and there is no gains tax for their holding (ever).  

This is all before title, tax, conveyance fee's, water hold, etc.

With inflation pacing higher than expected and with the Fed obsessed with a silly and arbitrary 2% number for inflation, don't hold your breath on significant drops for a bit.

One strategy I like to do is build in seller credits into my offers so the loan covers the closing costs, e.g. if you wanted to offer $500K for a property, offer $510K with $10K towards closing costs and that $10K is supported by the loan and can be used on the costs I mentioned above.

It sounds like you've made great progress in building your real estate portfolio, especially with the support of your grandfather.

I occasionally enjoy co-hosting (splitting costs) for client events with a lending partner but that is pretty rare as most lenders just want to hold "first time home buyer" classes/events or co-brand online ads for home buyers.  

In today's real estate market, several effective investment strategies include:Buy and Hold: Acquire properties for long-term rental income and potential appreciation.