Tour Guided Holiday For 1YO and 15YO in Asia Preferably

DP and I would like to take 1YO DD and 15YO DSD on an overseas trip - preferably somewhere like Vietnam. This year would be the best time to do it before DSD think it's really uncool to go on holiday with your parents and I think it would be good for her to experience other cultures especially in countries not as rich as Australia.

I was thinking a group tour would be good - just to take some of the hassle out of booking accommodation, working out where to go for meals etc. etc. especially as itineraries and bookings usually get left to me and I'd kind of like to leave it to someone else for a change.

But most of the tour companies have a minimum age of 4 or 6 for children and obviously DD is a lot younger than that.

So does anyone know of any companies that will accept a 1YO or if you organised a holiday yourself, how did you go and what tips do you have?

Neither DP or I are sit on the beach/by the pool sort of people so we're looking for something a bit more active.

Vietnam isn't a country where it would be easy to carry a pram. You would need to do a fair bit of slinging/carrying. Is your back up to that or would your DH take it on?
If you can't find a tour company in Australia there is a good chance that you could negotiate something in Vietnam.
Most of the more active tours in 'Indochina' assume that you will be able to ride a bike for short distances and walk hence the child thing.
If you can get another family to join you you might be able to negotiate a tailored itinerary.

ETA - Try ringing Intrepid. They have a Vietnam tour that is quite sedate. If there is a bike riding morning you could just elect to go for a walk instead.