I'm easy sheldon, don't take things the wrong way
what i post is based on experience, its not me who decides or makes the rules
it would be better if you could get them British passports, as you've said the cost of 3 settlement visa fees is expensivethou once here in the UK they could apply for a British passport, but even if you did apply for british passports the embassy might want you to register them and i think thats expensive thou not as much as a settlement visa (thou i'm sure you do not need to register them
)