Dana1003
I am not sure if your girls are 2 years old or 3.
If they are 2 than hopefully you will not have a problem but if they are 3 and look 3 you may have a problem.
Some CM's question the age of young children who look 3 but who do not have a ticket. They have even been known to make the parents buy a ticket for the child/children if the parents do not have proof the child is under 3.
The money can be refunded after the parents return home and send a copy of the birth certificate.
If they are 3 and I were you I would just pay for them rather then be embarrassed that I tried to sneak them in.
Please consider this as a friendly word of caution.
JMHO
Have fun at Disney!