Hello friend greetings to you. Hope are having good time there.

We can define a sidechain is the one that can easily attach with another chain. Perfectly said. But the chain which the side chain is going to attach must be the main Blockchain.

You have also defined the two types of side chain. In first case we have both side chain and are completely independent on each other in all aspects. The other is is when we have one dependent chain and the other is independent. In this the dependent chain is sidechain.

You have beautifully explained the function of sidechain in Steemit. It's really nice to read out your post here.
I wish you very best of luck here in the contest.