Home-made baby sitting harnesses (for sitting at table)
When our little granddaughter, baby I, was coming on holiday with us, we guessed there might not be high-chairs / baby seats available, either where we were staying, or in restaurants while eating out. So I thought I’d make a seat harness for travelling. Now we have 3 baby granddaughters, and, when they visit our home, our one purchased plastic booster seat is not enough. So we've also been able to use the harness at our home for the visiting babies. You can see Baby I using it, below, at the age of about 16 months. But she's been using it since before she could sit up properly on her own.
I'll tell you in detail how I did it on another post, so you can copy my ideas if you wish, and I will also give some other ideas I've found, if my approach doesn't work for you. My design, and those provided free by other people, are intended for personal use.