Might need a Mediator for help

Arizona
Lived and died in AZ but Trust and will are in Washington State. I a trustee live in AZ and the other siblings on both sides live in Washington. We are trying to settle an estate that is in a trust where there are two sides of the family, the stepson side us. and the real kids. A trustee on each side. step dad who we have been very close with for 30 years and the real kids who were not. It is too complex to give all facts. We want to do just what our parents wanted in the trust. We are considering having a mediator make the dissections.
This is after we have tried to work things out with the other trustee who has held things up for 8 months. We also feel that the other side will not agree to a mediator if we find one, probably only if they choose one.
What exactly is the process when you get a mediator.
1 what can we bring to the table
2 how do they base their decisions
We feel that it might be the best thing to do. but want to let the mediator know what has been going on since the beginning of the death of our stepfather.
Could you please give me an idea what to expect.
Thanks azsunWhat is the name of your state?

Give a brief description of the issues involved here. Mediation is most often applied when the issues are fairly simple and clearcut.

Are there co-trustees of the same trust here or individual trustees of 2 separate trusts?

Does either trust have representation by an attorney now?