[Users] separation of simulation domain

Hello,

I have a question about whether it is possible to separate the domain of the simulation. I want to simulate with a larger scale such as (1 million km )^3 , however it is too computation-consuming to simulate the whole domain with GR and it is not necessary to consider GR because GR could be ignored in such large scale. But in the region near center with high density , GR is important .

Therefore I am wondering if it is possible that GR is included in the center region ,say (1000 km)^3, but not included in the other region. However another problem is that timescale is also very different. ET's time scale is about ~ ms but what I need is around hours to days. Is there some suggestion for me to deal with it ?

Thanks,

Best regards,

Chia-Hui