*For younger ones have a special "quiet time corner" for the kids. This could include a table and chairs, Bible coloring books, crayons and other art supplies, Bible story books, tapes, puzzles, etc. They can have their own quiet time while you finish yours.
For older ones maybe have some time together with them before everyone goes to have their own quiet time…..
* Memorize scripture with them.
*Pray about concerns with them.
*Sing hymns or choruses together.
Then while you are doing your quiet time, they can read the Bible or a devotional book and then either draw a picture or write something about what they read.
Also sometimes share with them what you learned from your quiet time. This might encourage them to want to have their own time and allowing you to have yours. Just don't demand that they "get something" from every quiet time. This can create stress and make quiet time mechanical.
I hope some of this helps you. If you have other ideas or ways that have worked for you I would love to hear about them too.