A question about age groups and formations.

I have a Junior Formation for the European Championships 2015. The Junior formation has 15 dancers but they want to have some girls who are younger. I know the rule says you can be two years younger as long as over 50% are the appropriate age. But can you just guide me on who can and who can’t on the following date of births please:

Emma – 14th October 2004 aged 10 and 11 in October
She can, 11 this year
Isabella – 26th September 2004 aged 10 and 11 in September
She can, 11 this year
Amy – 30th November 2004 aged 10 and 11 in November
She can 11 this year

Amber – 27th May 2005 aged 9 and 10 in May
She can, 10 this year
Faye – 23rd August 2005 aged 9 and 10 in August
She can 10 this year
Ayla – 15th November 2005 aged 9 and 10 in November
She can, 10 this year

There has to be at least 7 dancers who are 12 to 15 for the above 6 dancers, ages 10 and 11 to participate in the formation.

I await your advise,

It is my pleasure,
Good Luck to all, Bill