Wow, what an interesting conversation! I live in Australia, my daughter is only three months old but when it comes to the multilingual side of her upbringing I'm a bit worried. My partner is Australian, however is currently studying Swedish because he wants to learn so that he can talk a bit to Ava when she grows up as well as talk to my family when we go home etc. I'm Swedish and currently I talk both Swedish and English to her, my Parents in Law are originally from Hong Kong and sometimes they speak cantonese to her and sometimes English, then we have some very close friends that speak Persian or English to her :/ Do you guys we all need to start being a bit more consistent?
Also, regarding people wanting to give the child sweets that you don't allow. Quite seriously, I would just tell them to back off. My sister back home doesn't give her kids sweets at all, they don't even drink orange juice more than once a week and have been taught that candy is for grown-ups, and instead they get to eat fruit or a skorpa which they really like anyway. I think some ppl just need to understand that children are taught to like candy and if they really like banana it is so much better for them to get that as a treat instead. :D
Anyho' that's my two cents worth :)