What in the savegame do you have to edit to change the dynasty name then?
Well my suggestion would be as follows (for the OP's case of changing dynasty of the son):
- Open Save game file in a text editor (Notepad will do fine)
- At the top of the file is a line called 'Save = TOSC'. The TOSC is the tag of the realm you saved as. In this case Toscana.
- Copy the tag (TOSC) and press CTRL+F (in Notepad) and search for the next occurence of the tag. This shows info about who rules the realm and which titles are held by the ruler etc.
- There will be a line called 'DNA = "99999999999999". This is the DNA string of the ruler. So if that is the person you want to find, copy the digits (no quotes) and do another search for that.
- Now you have the entry for the ruler, and you can make changes for that character if needed.
- But what OP wants is the Dynasty ID, as he will need that for his son to become a DiCanossa. So write down what the 'dyn' value for Mathilda.
- To find the son, you can use the id line for Mathilda to find him the easiest. Since she is his mother. Now copy the whole 'id = { type = 10 id = xxxxx }' line, go to the top of the file, and press CTRL+F again.
- Now paste the copied line into the search field and change 'id' to 'mother'. That way you are now search for any character with Mathilda as the mother. Finding the son should be easy.
- Once you find him, you just change the 'dyn' value to the one from Mathilda's entry ... and on next reload, he will be a DiCanossa.
Now this might look complicated, but once you have tried it once or twice, you'll get the hang of it.
Just remember to take a copy of the save game file BEFORE you edit it.