It is possible for those two IRAs to joint-venture to purchase an investment property.With a self-directed IRA, it is not "you purchasing your first rental home", however. 

   My father and I bought a home in 1996 joint tenancy right of survival mortgage. 

It's a loan modification or likely a ch 11 BK prospect if they want to attempt to keep while retaining ownership of the property. 

With QuickBooks Online you have free ACH as a Landlord.

The lender simply needs to make each of your jointly and severally liable for the loan. 

Since being on here I quickly realized how there is such a vast difference in the feeling in the air I get in Bigger Pockets compared to other groups (some groups in FB, in which I intend to leave the group due to not getting any real sense of value, but more like a bunch of vultures wanting to make easy money by preying on (ex: Joint Ventures) with the newbies).

But currently as is with the portfolio that has been built up, the positive net cash flow is 100k a month.Any help would be appreciated, joint ventures are welcomed. 

But currently as is with the portfolio that has been built up, the positive net cash flow is 100k a month.Any help would be appreciated, joint ventures are welcomed. 

So your final decision might be the answer you make on those 2 properties and any decision might be decided on the debt question of good debt versus bad debt.If you have any benefits by purchasing  an apartment complex as a controlled ownership and by benefiting from a Tenants in Common joint venture association that will contribute to an apartment complex purchase and allow your keeping control of that property on a daily basis regardless of your ownership percentage.  

You don't want to run afoul of non-discrimination laws.Good rental criteria requires all adults (18 and older) who will be residing in the unit to apply, pass the screening process, and be listed on the rental agreement as jointly and severally liable.