Here is an idiea for you:
First though - Be a gracious host to your parents for as long as they need your help. You may not have another such opportunity and if you don't take advantage of it you may live to regret it.

Anyway, why not start a few of your precious seeds in cups and scout out a good place to put them outdoors. It's the right time of year. You can get them outside before your parents even know what they are. Just start some other vegetable and / or flower seeds along with them. Tell them your experimenting with a new hobby.

You can then get going with the indoor room after your parents are safely back in their repaired / rebuilt home.

good luck