Hello.
We are small business based in St. Louis and we have a branches in Poland and Colombia. Is it possible that we can add those remote streams to Blue Iris if we buy it?

It's possible, Blue Iris doesn't necessarily care. The traffic flow is that the server needs to be able to reach your camera. So whether that is directly over the Internet or via a VPN tunnel is all up to you. I would definitely recommend testing it with an eval first as that will still largely depend on network quality. Streams work great when they're local but with that distance you could be looking at latency problems (but - maybe not)

Is it possible that we can add those remote streams to Blue Iris if we buy it?

I guess it depends what you want out of it. If you are wanting to record only in the USA (One BI5 licence) then it will use a lot of bandwidth = $$$ in internet fees and may have other issues. If however you will be recording locally at each site (Multiple BI5 licences), then it wouldn't. I think you need to define what you are after.

For example if you went for the local model, you could view the remote sites by using Teamviewer or any similar software just to check occassional footage from the other sites. You can also view a licenced copy of BI5 from another licenced copy.