Hi, I have had about 20 hamsters over many years , one of which had 11 babies.
18 months is quite old for a hamster, they are certainly 'pensioners' by then. I have never heard of Syrian Hamsters living together, introducing hamsters for mating requires constant supervision as they will fight to the death! The babies will start to fight from about 6 weeks. I presume you had dwarf hamsters.
I have had russian hamsters and did not find them so appealing as they could not be cuddles and had a tendancy to nip, but they could be kept in groups.
I have to disagree that hamsters bite, or hate being handled. In my years of keeping hamsters, I have never been bitten, and handled my hamsters everyday.
I think SYRIAN hamsters are a perfect pet especially for children, they teach respect, patience and about death ( difficult at times) and can be left at home for a weekend.
Hamsters require taming, they should not be bought from a pet shop and expected to be picked up straight away. At food times, they should be stroked, then over a week or so stroked down the sides, then very gradually, picked up. Each is different, sometimes this takes weeks sometimes days. My sister, who has cerebral palsy, and can be quite heavy with her hands still has hamsters and after a few weeks of taming, she is able to handle her hamsters, they giver her so much joy.
Mine would come out in the evening when called, lick food from my fingers, and show affection.
I have loved Syrian hamsters, an hate to hear that they do not make good pets, they just require a little work at the beginning, much less than training a dog!
The only reason I do not have hamsters now is that we moved to the country and now have a Jack Russel, who would see the hamster as more of a snack!
I would reconsider especially as your children have bought a fancy new cage, One Syrian hamster, tamed with patience and care will make a perfect pet.