If you want to grow, then scaling within control is good.

Pricing tools that exist on the market are decent, but you also need to know how to control it, otherwise, it will go nuts with unrealistic rates far out and extreme last-minute discounts. 

What's the exit strategy if any, for the investor, given that, with 50%, he has no control and the market there is illiquid, especially when the HELOCs out of North American properties are much more expensive.Properties in Costa Rica are already expensive and I've tried many times to make a potential investment there work and it's never worked with the figures.

The sooner you regain control, prove that you fully intend to enforce the terms of your lease, and that you will not be 'played' by their recall of events or documents, the more effective this action will be.  

I am looking at a 5 unit building that I want to do a condo conversion on. 4 units would be vacant 1 has a rent controlled tenant in there who does not want to move.

With so much out of our control with military orders, we were fortunate.

Here are a couple of ways you could structure the deal:Lease Option with Seller Financing: You could lease the property with an option to buy later, allowing you to rehab it while giving the sellers time to find a 1031 replacement property.Seller Financing with Deferred Payment: Structure the seller financing with no immediate payments, allowing you to refinance once the property is appraised, and the sellers can complete the 1031 exchange when ready.Escrow Holdback: Transfer the deed into an escrow account, giving you control without immediate transfer, so the sellers can take their time with the 1031.Third-Party Facilitation: Use a qualified intermediary to hold funds and facilitate the 1031 exchange while you refinance.These options allow flexibility for both you and the sellers.

It's a way for them to maintain control over their material and keep their audience intimate. 

See what other controls they offer.  

Here’s my recommendation to get it under control: For a quick fix, start by sealing up any gaps using acoustic caulk around outlets, baseboards, or other small openings.