I have been thinking recently about this, but I haven't really found a clear answer to this online. Almost all examples consider only two things, a stationary observer+Moving object. Now I wanted to know what exactly would happen if there was more than one observer, each one affecting spacetime differently (Through Gravity or Velocity), and each one can observe one another. As an example, let's remove velocity TIme Dilation and only use Gravitational Time dilation for now. Also, let's specify who exactly are the observers and where they are exactly.
The first one is Tim. Tim is orbiting around a Supermassive black. His clock will be ticking the slowest
The second one is Kim. She is on Earth. Her clock will be ticking on Earth's Scale
The third is Jim. Jim is in the center of a big void area (Affected mostly by his own gravity). His clock will be ticking the fastest
Now let's assume they can "observe" each other "Simultaneously"
Now to Kim, Tim should seem like he's traveling into the future. To Jim, Kim would also seem like she's traveling into the future, but at the same "time", Jim would also see Tim as he's traveling into the future, but because of the gravitational differences between each other, technically speaking, Jim should see Both Tim and Kim as traveling into the future, but he would see Tim as he's traveling into the future more so than Kim.
It's a headspinner this one, so I've attached an illustration to explain my point. Let me know what you think.