Kid friendly alternative to the sigg ?

I have a 1.5 ltr Sigg it really holds 1.6ltr and two 1 ltr Nalgene narrow mouths , both children have a 330ml kids Sigg but the youngest can’t manage to drink for it and the oldest needs a bigger bottle . Was looking at the Nalgene grip’n’gulp for them , but wondered if anyone here knew if a better alternative was available. I am in Scotland but can easily order from the States if thats the only place to get them , i was also looking for the straw attachment for the Sigg’s but can’t find em anywhere maybe they are only for the people who drive F1 cars .