@Micki Ray Harper In a quiet title lawsuit, you are obligated try to find people who should be defendants. The complaint must describe the steps you took to find people who should be parties to the lawsuit. That is to basically keep you honest, so they judge can tell you tried. You are not obligated to be successful.
At one time, I told people to spend money on a skip trace so they could file the in personam QT lawsuit (the one where you can served lawsuit papers on all defendants) and avoid the expense of the in rem QT lawsuit (the one where you need a GAL). But, today, most judges are requiring a GAL anyway. So, just give it your best self-help effort to find them, and then let the GAL do his or her job.
As far as an ejectment lawsuit, the real question is, was the property legally abandoned? If you took DIY possession, was it legally allowed because the property was abandoned, or was it illegally obtained and doesn't mean anything when it comes time to file a quiet title lawsuit.
If legally abandoned, that means the owner is gone, has no intention of coming back and no intention of ever doing anything with the property. The question is, what is the intention of the owner, not what would a reasonable person think is the intention of the owner. That's hard to figure out sometime. The safest thing is to file an ejectment lawsuit. But, if you can find the owner to serve ejectment lawsuit papers on him, you can't get an ejectment order. So, that was a waste of time and money, right? All you can do then is just assume it is abandoned, take the risk, and take DIY possession like your Dad did. Some lawyers will file ejectment lawsuits and ask for service by publication, but that is not allowed under the rules. Judges will sign off on it, but any judgment obtained by a method of service that is not allowed is void. So, all that time and money and really you are not better off than if you took DIY possession. Of course, that's only when you truly cannot find the owner.