I'm getting started with KoolGrid, and it's great. I've built a series of pages with single files successfully. Now I need to get a multiple table hierarchy working. Once that is in place I will buy the full version. I will gladly pay someone to walk me through this. Is that possible?

Have you attempted to go through the documentation page?
https://demo.koolphp.net/Examples/KoolGrid/Hierarchy/Three_Levels_Hierarchy/index.php
Let me know.

Yes. I have studied it in detail, and attempted to break it down and reproduce it. I have been successful at creating lots grid pages for single tables, so I have paths, installation, etc. working.
For a hierarchy page I have created database connections to 2 tables, in the same script and the code ran without failure, so I think that part is correct. When I try using $grid->MasterTable->AddDetailTable($grid_child); to display a linked table as in the hierarchy example, the code does not fail, so I'm not making syntax errors, but only the parent table appears. There are no link arrows to lead me to the child table.
As always with KoolGrid, I am assuming there is either a property or two I have missed, or I'm using the properties in the wrong order. I feel I am very close. I will gladly pay someone $100 on Paypal or any other system to look at my code and provide the missing step.
Thanks in advance for any help anyone here can provide. KoolGrid is great. I sold a project to my client on the basis of the Hierarchy demo. That is the type of interface I need to create.

Email me your table structure SQL with some sample records in each for the tables involved.
Put you name timezone in the email.
Tell me the table drill down you are wanting.
I'll see if I can set it up for you first, then I'll email you a link to check it out to see if it's right.