Legal Advice With Land Transfer, Thai Wife Passed Away

Hi everyone

if anyone can help me with some legal advice and what process to follow for my situation, I would be very grateful, here goes:

My wife sadly passed away recently who was a Thai citizen with British Citizenship. She did not make a will (that we know of) and we have land which is in both our names and she also has land that is in her name only that she bought after we got married.  I’m a British Citizen living in England.  My wife has a son who is a Thai citizen from a previous partner and her mother is a Thai citizen and still living.

Me and the son have the land documents in our possession, but my wife enjoyed her secret surprises and mentioned other land and a house that she supposedly bought after we got married for which we cant find any documents. Therefore, we assume that we need to run a search on any additional land she might have acquired and any bank accounts. We also want to start the process to secure the land that we do have documents. My wife always told me that we should split the land 50/50 with her son if she were to die, which I’m happy with doing.

Does anyone know the best legal approach here? Should we form a Trustee with me and the son and would this allow us to approach the land office and banks to do a search for other land, property and bank accounts? Can we already successfully request searches are done with just the Thai death certificate?  I’m a foreigner of course so would it be easier to have everything in the son’s name and split it all later?  There is the question of my wife’s mother who to my knowledge is not aware of any land owned, is she entitled to a share? I don’t believe my wife wanted her to because of a few of the sons have gambling and other issues which she kept a distance from.

I would also welcome anyone’s advice for a choosing a lawyer, it would help me if they speak English as well as Thai.
Any advice would be great, thanks.