Reactive Power Absorbed By 3wdg Trafo From 69kV Bus

Sounds like your generators might be turning too slow. Just a guess.

Measure, measure, measure and start turning off/isolating/altering this network's elements till you find where things change in an unanticipated manner(within safe operating constraints naturally).

If you don't know what is broken find out what is working.

I may firs ask why this topology with two 3 winding transformers having the same voltage for two windings? Did you try to have all 3 TGs connected each just to a 13,8/69 kV two winding transformer?

In general 3 winding transformers need more reactive power to work (they have larger cores) and your TG might not have enough resource for this. You can see this by changing the TG's power factor. Moreover, the load on the tertiary might mess up the things.

Eventually, if it's just a model it means you can still make changes easily.

PS: Next time when you ask for an answer try to give more information (generator power factor/reactive power, loads power, even what you suspect it might be the issue, the reason for the topology...)

...and a sketch is always good.

I had to read the OP 5 times to get a picture in my mind (which may still be flawed) Paragraphs would be good too.

Yes, you're right. I forgot about it but it's true that for engineers sketches, drawings or any kind of image are appreciated and moreover, offering a hell lot of information. In many cases if you have the "picture" all you have to do is ask the right question.