Well since I did a Snips sibling yesterday this seems like a logical follow-up
Though I’ve had this thought quite a while longer than Snips and Teddy

Anyway here is Snails with Squirmy as his little sister
I changed her into a unicorn just because my headcanon’d families tend to be “interracial” so I switched it up a bit.  Also she’s supposed to be a little older than the baby in Mare Do Well I think.

ANYWAY she’s young enough that their parents take a good deal more care of her than Snails does but when he needs to he watches over his sister happily and patiently.  Meanwhile Squirmy is well….squirmy.  She’s kind of ornrey and constantly on the move and I guess sort of in her “terrible twos” so to speak.  As she gets older Snails will probably teach her to mellow out a bit but she will probably still be a bit independent and impatient.