Well, this is a broad question. First, it will take a long time for the kids to get the visa. Second, if they get married, the petition is cut off. Third if the parents stay too long outside, they might lose the green card. In turn the petition will die.
Therefore, you need to be very careful how to proceed
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I agree with the points made by my colleague: first, such a petition would only remain valid as long as the children remain unmarried, and second, it would only remain valid as long as the parent maintains permanent residence - and remaining over there with the children risks losing permanent residence via abandonment. This petition would take a very long time.
I would make this additional point: if otherwise eligible, the best course of actual for the parent may be to remain here long enough to naturalize as a citizen. Once a citizen, the cases would be in a different category that would 1) take less time, 2) not require that the children remain single, and 3) if the children got married, allow them to bring spouses and children. In addition, once citizenship was obtained, the parent could then join the children without fear of losing her own status or invalidating the underlying petitions.
Speak to a lawyer for further advice.