Advice needed - 2yo constantly slapping 5yo.

[Molotov]

We have 2 dds aged 5.4yo and 2.2yo. They are lovely girls who get along mostly, but have a problem atm.

Dd2 slaps dd1 a lot. It happens sometimes when they play together but mostly, it's quite random (no reason for it). Dd2 will do it right in front of dh and I.

I feel bad that we have resorted to raised voices and have tapped her on the back of her hand recently. I hate that. But, dd1 is so shocked and upset that I really need dd2 to understand ... but I know it isn't the right approach, which is why I am looking for advice.

Dd2's language development is a little slow, imo, and I am seeing the HV this week to get their advice about this. I understand that dd2's slapping could be due to frustration, but maybe I'm just assuming connections?

It could be. I would keel very close to dd and try and intervene before it happens. Hitting her isn't going to work as just sends a mixed message.

She might be doing it for attention. My 2.6 year old kept sticking her hand somewhere when I'd told her not to. She would look at me deliberately while doing it for my reaction!

My ds3 has gone through a phase of hitting his older brothers, but I think he's coming out of it now. We use a time out on the bottom stair. He gets told off the first time he hits and told no hitting. If he does it a second time he gets told again, and told that if he does it again, he'll go on the stair. Third time, on the stair. He should stay there for a minute, but often gets up and cries. He then has to say sorry to whoever he hit, i repeat 'no hitting', and it's forgotten.
It takes a while to sink in, so I'd say be patient and you'll see results as long as you keep on showing her it's not ok.
(Agree with pp, tapping on the back of the hand could be pretty confusing, since she's so young.)

Ds3 is 2.5, by the way.

That for the practical advice. We will give the bottom step a try and see how that works (fingers crossed!)