7 hours ago, Crash999 said:

That's a very good thought and could simplify things a lot given no financial requirement. I'm on a B-visa and uhh... I guess an annual extension. To be honest I never gave too much thought about my own visa status as our company employs someone to tell me where to go at Chaeng Wattana and what to do. I should have paid more attention.

If he could be a dependent then that would be an interesting alternative. Only drawback is if I were to go elsewhere in the region for work for a year or two then he'd have to get another visa, though I suppose we could cross that bridge when we come to it.

If you are on an extension of based upon working for a company your father can get the extension Maestro and I mentioned earlier.

I assume you wife and other family members are probably on the same extension he would qualify for as a member of your family.

He first would need a non-o visa that he should be able to get at a embassy or consulate with proof you are here on an extension of stay.

He could also enter visa exempt or a tourist visa and change a 90 day non immigrant visa entry at immigration. See: https://division1.immigration.go.th/download/1551323256580.pdf

If you were to leave the country and he wants to remain here he could change the reason for his extension to one based upon retirement without needing a new visa.

7 hours ago, ubonjoe said:

If you are on an extension of based upon working for a company your father can get the extension Maestro and I mentioned earlier.

I assume you wife and other family members are probably on the same extension he would qualify for as a member of your family.

He first would need a non-o visa that he should be able to get at a embassy or consulate with proof you are here on an extension of stay.

He could also enter visa exempt or a tourist visa and change a 90 day non immigrant visa entry at immigration. See: https://division1.immigration.go.th/download/1551323256580.pdf

If you were to leave the country and he wants to remain here he could change the reason for his extension to one based upon retirement without needing a new visa.

Thanks for the additional info and the link. 
 

It would be much easier if he could enter on a visa exempt status as that saves him multiple 4-hour trips to the nearest Thai embassy. Then it seems he needs to change to the 90-day non immigrant visa rather quickly. From there what's the process to make that one year? This is also an "O" visa is that right? 

 

Do you know of any reliable agents who can hand-hold someone through the process at immigration? Googling it results in quite a few options.

5 minutes ago, Crash999 said:

It would be much easier if he could enter on a visa exempt status as that saves him multiple 4-hour trips to the nearest Thai embassy. Then it seems he needs to change to the 90-day non immigrant visa rather quickly. From there what's the process to make that one year? This is also an "O" visa is that right? 

The procedure and requirements I posted would lead to him getting a non immigrant O visa. 

Then during the last 30 days of the 90 day entry he would be able to apply for a one year extension that is based upon your extension for being your father.  Since your employer assisted with your and families extensions they should be able to help with your fathers.

Getting the extension will require about all of the same documents that is needed for the visa application.

Your birth certificate may need to be legalized by your embassy or an authority of the country that issued it.

 

So he can come in on a visa waiver, convert to a 90-day non-O within fifteen days of the expiration of the visa waiver, then within the last 30 days of the Non-O, get a one year extension based on being a member of your family.  As Joe says, if you must leave the country for any reason, he could switch to an extension based on retirement.  The only "gotcha" here is to be sure to have the financial requirement satisfied two months before he would apply for his own extension. Joe's advice always points out the simplest and most effective method.  Note that there is no financial requirement if you do it as Joe advises.