Is it permissible to make up missed prayers from childhood while sitting, knowing that standing causes dizziness due to illness, and making them up while standing might take a long time?

A child under the age of puberty is not obligated to pray, and once they reach puberty, they are not required to make up for prayers they missed before that age. If prayers were missed before puberty, you are not required to make them up. However, if they were missed after puberty, you are obligated to make them up immediately, even if it was due to laziness. You are permitted to pray while sitting if standing becomes difficult for you.