Q.Cilantro indoors
I planted cilantro by seed, also last year with success. My daughter wants some for her window sill that gets great morning sunlight. The seedlings have sprouted and now are about 2 1/2 inches high. Do I cover them 1/2 way up with soil now? I cannot plant them outside, as we live in Mn. How do I care and what do I do now? I am scared they will become too tall and fall over? HELP!!!

Are the seedlings floppy or spindly as well? If so, you might have leggy seedlings, which are caused by insufficient light. You can read more about leggy seedlings via the following article:
https://www.gardeningknowhow.com/garden-how-to/seeds/leggy-seedling.htm
If there is room in your seed flats, you could carefully add just enough soil to the base of the cilantro seedlings to support them upright if they are really in danger of falling over.
For more information on how to grow cilantro indoors, please visit the following link:
https://www.gardeningknowhow.com/edible/herbs/cilantro/how-to-grow-cilantro-indoors.htm