Hello!

In theory, you, of course, shouldn't. The manual states the maximum weight they guarantee for the stroller to be OK with.

On the other hand, most strollers, even if maybe the large ones, CAN hand a bit more in the seat. The more so if you won't fill the storage basket as there is also some weight capacity - so, for example, if the stroller's basket capacity is 2 kg and you put nothing in there, the stroller should hold up to 17 kg, theoretically. I did overstrain a few strollers occasionally, putting even 2 kids inside when in desperate need; however, they were larger and sturdier models than the Aigo buggy is.

I must warn you that this, as an affordable and rather small, compact model, may get damaged if putting a heavier child inside regularly. Usually, that means the folding can start to be lopsided and not work on one side; the wheels can get lopsided; and the frame, in extreme conditions, could break (or start to crack).

All in all, a bit (maybe 1-2 kg) should be fine, at least from my experience. The smaller the pushchair, though, the worse it will handle that, and you do take a little bit of risk of damaging it. In such a small buggy, a larger child could also feel quite cramped... So my advice, here - do use it if it's only occasionally, but for everyday rides, rather sell it and get something a bit more substantial, something mid-size with a wider seat (like a Kinderkraft Grande, for instance, or an Oyster Zero).