Cream (fresh or condensed milk) to "season" the soup or sauce, you need to rub it well with, for example, a little flour mixed with cold water, add a little sauce or soup and then pour it into the pot. There will be no lumps and the cream will not turn over.
The cream can be quickly thickened and acidified, adding a little lemon juice or a few drops of vinegar to it and keeping it warm.