You are right and there is a big difference. There is always the danger for them to embrace heretical ideas especially on the Eucharist and end up being separated from the Catholic Church. The only Church that Jesus founded (Matt 16:18-19).
I donít know all the background of the story but for what you have said, I recommend you to pray for the parents of the girls, the girls and for this situation in general. Also pray the Rosary and ask our Blessed Mother to intercede in this situation. Under the advocation of our Lady Mary Help of Christians, for she is our helper (our Auxiliatrix). Ask your guardian Angel too, to intercede with the guardian Angels of the parents of the girls and the girls in the name of Jesus.
When you are with the girls I also recommend for you to read the Bible to the girls (or ask them to read for you), especially (John 6:22-71) (Luke 22:19-20) (1 Cor 11:23 ff). Pray together with the girls also for where two or three gather in Jesusí name, He is present (Matt 18:20).
Also ask the girls to watch the youtube channel of Father Mike Smith. He is very good explaining the Faith to the youth. Here is a link to his channel:
Youíll be in my prayers as well.