If you have a child who is too small for her first bike, you can bring her along on leisurely rides in a carrier that mounts over the rear wheel or a separate stroller you tow. Go slow and easy, and keep the rides relatively brief so the little one doesn't get a chance to get antsy.
Kids can get cold quickly.
On top of that, they're just riding, not pedaling. Because carriers sit so high, they throw off your center of gravity. Ride cautiously until you get used to how the bike handles. Another option for older kids is a bolt-on tandem that lets your child hold handlebars and pedal while you provide steering, power and balance. These can be good precursors to a child's first bicycle.