If it is a larger house and the renter group is families consider that moving in the school year is less common.

I imagine a lot split would also significantly increase cost of utilities as now I would have 3 hookups in that scenario.I am also concerned what would happen to that sweet 3.25% 30 year fixed mortgage I have, which I don't want to create any risk over in the slightest.Any advice on how to frame my counter arguments would be incredibly appreciated.

We want to travel and invest and are considering converting this short term rental to a long term rental to avoid sales tax, paying utilities and general management of the property. 

The market has definitely gotten more competitive, and it’s common to see BRRRR deals over $250K, especially given the high demand/appreciation in the area.

They need to do all their due diligence including understanding the value that will be added by the ADU, the finance options available, the consequences of adding the ADU (rent control, property taxes, rental limitations, etc), etc.Good luck As with all things, it depends on the investor and the equity.If they are able to leverage existing equity to buy it under a HEL or HELOC, then they are adding equity with no out of pocket expenses, and adding immediate and longterm cashflow to existing stock.We like ADU's because there isn't more land being created in our city that is landlocked...but there is more density available to those with large lot under-utilized sfh.In my market, it typically costs $2 to add less than $1 of value on single build ADUs.  

Common fees will include a set-up fee, a leasing fee for each turnover or a lease renewal fee, marking up maintenance, retaining late fees, and more.

If the property is sub-metered/ if you intend to have the tenants pay utilities make sure to mention that to them. 

It was common back in the day.

Most investor utilize short term hard money debt to scale their flipping operations where the lender will fund 80+% of the purchase price and the rehab budget which can allow investors to work on multiple projects at once.

2-4 units are not that common, but builders are building them more now.