On Saturday, I met an Italian lady who lives in London. She and her German husband speak their respective languages to their children but the children (well, the older one, as the younger one is only 18 months old) only answer back in English, though they do understand.
Although her son has a certain degree of trilingualism (he understands 3 languages so could be called a 'passive trilingual'), she sees this situation as a 'lack of success' in getting her son to be trilingual. This is especially the case as she knows of children who speak their three languages beautifully. So we discussed possible reasons for this (relative) failure. She felt these were mainly due to work and her child's personality.
The fact that both she and her husband work full-time in demanding jobs could have an impact. They are not around much to pass on their languages and certainly this must make things harder. However, they do employ Italian-speaking nannies ... so, theoretically at least, the son should be exposed to the language as much as he would be if she were at home. Perhaps the nannies don't actually speak Italian to the child? Or perhaps nannies are not as important as parental input?
Perhaps it's something to do with the child's personality. There may well be children who are more easily coaxed than others into speaking troublesome foreign languages ... I wonder if her second child will be more likely to speak the other languages?
She feels that the only way for her kids to learn their other languages is to send them to an Italian or German school, but which to choose? And that would mean lots of upheaval as they'd have to move her son away from the school where he is settled and probably move house.
We thought that perhaps an after school or Saturday language club could help. But obviously, fitting these all in is a challenge as you'd have to find a club for each language, and they'd have to be at different times. And then weekend clubs eat into the already limited family time that they have. Not an easy task!