Okay, get this. My parents' parish has dancers at the 11:00am mass. It's really quite horrid. The last time we were in Atlanta they made my husband and I attend the mass with them because we didn't believe them. It was worse than had been described. My poor father refers to them as the Vestal Virgins, I call them the Whirling Dervishes. At any rate, for an orthodox Catholic, it's like watching a train wreck.
It is now your duty to inform your parents that the practice of liturgical dance is not only banned in the US but also renders the Mass they attend, illicit. I battled this with the pastor of my (former) RC parish and won - but only by making the time to address the issue with him. When that could not be resolved, I wrote to the diocese which, no surprise, supported the pastor. Undaunted, I quoted from the documents posted in the link at #5, summarizing with the statement that "all Catholics are entitled to a valid liturgy". That was it! They could not refute those documents.
The only way to stop this practice is to address the issue directly with the pastor and, if necessary, the diocesan Director for Divine Worship. Are your parents up to this? If not, can you do it for them? Should the letter writing campaign fail, send copies of ALL correspondence to Francis Cardinal Arinze, at the address posted in link #5. This is your Mass and you and your parents, are entitled to a valid liturgy.