Welcome to the forums,
At 5 weeks of age, the chick should be able to perch and climb around, the fact that the parents aren't feeding the chick as much as they used to is also normal because at this point your chick is well on its way of being fully weaned.
In order to avoid a double clutch it's recommended to separate the mother and place her on a spare cage.
It's great that the chick is trying out the seed mix and by paying a closer look, you will be able to tell if the chick is able to dehusk the seeds and eat them.
Besides the seeds, you can offer your chick fresh foods, like sprouted seeds and leafy greens. Baby spinach leaves are usually a big hit with chicks.
Egg food is also a vital component during the weaning period and should be readily available to the chick at all times.
If the chick is unable to reach the food/water bowls then you can place a little feeding station at the cage's bottom and also place a water bowl (keep water level shallow).
The chick is able to be hydrated from the father's feedings and also from eating the fresh foods, so it's not a worry if you don't see the chick drinking water.
Even though your first breeding adventure is almost finished, you can still benefit a lot from the information found on the sticky threads at the top of the Budgie Breeding section's main page.
You start with this link and pay special attention to the weaning part: https://talkbudgies.com/articles-budg...me-chicks.html