There is an EU-funded project called FOMENTO: "Fostering Mediation in cross-border civil and succession matters".
This project has published a research report that contains very interesting
chapters about the mediation in various European contries: https://www.fomentonet.eu/wp-content/uploads/2018/09/FOMENTO-Research-Report_mediation-in-cross-boder-succession-conflicts-1.pdf
.