A sequel! How brilliant! You have made the sonnet look deceptively easy here, when we all know they're anything but. I love this continuation of the story and can imagine them as a series of children's books with fun illustrations, both poems have all the right ingredients for it. I can't nominate it on a Sunday but I don't doubt I'll be beaten to it.
So well done Mr D! :-) x
=^.^=

Hello Mr. D I'm so pleased there's another of the adventures and that the mice got their moon cheese.. I wonder if they're happier now, I'd bet my last 10p on it lol
Take care,
Em x

I love the ending line.

There’s a few lines that may need some help. For instance,

“ They watched a moon of cheese begin to climb.”

^ when I read it, I read as if the moon of cheese was starting to climb, but I feel like you meant to say the mice begin to climb, right?

So Possible suggestion if that was your intention:

The sun dissolved behind the seesaw mates,
they watched a moon of cheese and off they climbed
The mice all squealed, “we'd like to have a taste,
but how to reach a moon so high and fined?

Then this line:

The elephant so hard the mice did fly…

^ what did the elephant do?

The elephant jumped to make the mice fly <- I’m not sure about the meter in this suggestion though. Hmm … idk

Three mice wanted to taste a moon of cheese <- the meter is a bit off with “wanted”

^ three mice just wished to taste a moon of cheese?

Excellent, Michael. These are turning into quite something. More, man, more. I would agree with Lucero, however: the "wanted" is definitely off there.
All the best as ever,
Ben