Hi

I have two children the youngest 21 mths .... I would ignore the 'tantrums' that she pulls when you want her to sit in the chair and just sit her there then distract her ... she will forget all about being in the chair i promise. I just feel if a 13 mths throws a wobbly then gets out of sitting in the chair they will learn to do the arching of the back and more screaming will get her more play time all the time. I honestly would try to ignore be firm and tell he NO mummy wants you to sit here for lunch dinner or quiet time ' So you as mum can feed her or have 10 mins for you to do whatever ... she can still watch you .

Cheers