I would like to split some states half and half to different regions. Example
1) half of New Mexico as West Texas and the other half as New Mexico.
2) Texas to split into three regions Southeast, South Texas and West Texas
If "West Texas" and "New Mexico" are individual values in your dimension you are able to group "Less aggregated". As an example if Southeast,
South Texas and West Texas is not an entry in your data you should be able to create them based in longitude latitude creating a "Polygon" for each region.
Hope it helps.
Have a nice one.
It would be helpful if you can provide a sample dashboard .