Wish I knew what all these TLAs (three letter acronyms) mean, such as DD, DSIL, and so on. They're not even three letter, are they? But I still don't quite understand what they mean. I suspect the DSIL is either the daughter or son in law, but can't be both of course. I also suspect the DD is the husband, but not entirely sure.
Regarding grizzle, I'm sure most Americans know what a grizzly bear is. It's the same root as grizzling. Anyone with a bad temper, or fed up and having a whinge or a moan, will understand what grizzling is, it's just the verb from the adjective 'grizzly'.