I think it's rude. If you can't be bothered to host a party then don't, just have a small get together with family and close friends so that you can ask them to bring a plate and not feel tight.
Also - do you have to buy all 3 kids the same thing? What if you're child is really close to one and not the others? I think maybe the 3 kids won't feel so special too as it's not just about them iykwim...