Already plenty of good advice above, but there's one piece that is missing. 

So, Anca, your parents can 1031 from one property into more than one. 

One of them is in TX, another one in MA and I am not sure about the remaining. 

How does one do that?

Nature campaigns, direct mail, text services, accounting, etc all in one place. 

We’ve also found that at least one of the authorities (Jefferson county) started to run some kind of property specific rental comps which can also affect the max they’re willing to pay. 

At one point years ago, I toyed with the idea of owning giant apartment complexes in multiple cities.

@Audrey Sommer you have some good comments above (and some funny ones too) but just to confirm, what you were told is not accurate.  

@Allende Hernandez what happens if one or more occupants move out and the others stay?

Plus the street isn't a busy one.