Ok,, first of all.. try to teach them during eating...
1) Tell them to sit on the chair propperly..
2) Perform a doa' before eating..
3) If they use their hands for eating, teach them for beeing very carefull so the foods will not fall out from their plate..
4) They should know which fork to use, how to tlit the spoon to sip their soup, how to fold their napkins at the table, how to bite their cookies and even how to chew their foods..
5) And lastly,, after eating, dont let them use a lot of water for washing hands ~make sure they're clean and dont forget for the doa'..
After they master in the eating habits, go on with the other works and habits.. Always reminds them for beeing good manners to everyone, at any place, and on any time..
Subhanallah,, once they know, they'll do it for life.. Thus, if there is a family gathering or maybe at the shopping complex, and even anywhere, parents will no longer worry about their children in mis-behaving on doing work.. But, they could show their islamic attitudes.. So,, they could be the good examples for the others, right..?
Besides learning for good manners, they also learn how to be dicipline.. For example,, they will know for keeping-clean during eating,, and there is a hadith that says "Annazafatu minnal Iman".. Another example, they will learn for not beeing misspend and there is also a hadith that says "Innal Mubazireena Ikhwanul Syayathin".. So,, these diciplines could relate them more about Islam.. and Insya Allah,, they will be the great next generation of ummah.. :)