Robins nesting in garage, feeding, fledglings

A story in several parts:

We have a garage used for storage (round the back of the house and modern cars are wide) and we tend to leave one door open for ease of access.

We noted robins flying in and out of the door, but couldn't see a nest.

Then we noted magpies scouting the area, and so closed the garage door hoping the robins would adapt to using the top hung casement window which is always ajar because peacock butterflies (after finding some trapped in the garage in spring, years back).

Thankfully the robins were soon seen zooming in and out of the small gap.

Having an adopted family, we thought about feeding.

The adults allegedly like dried meal works, so we hung up a garden feeder near where they perched, and sure enough they were soon stopping for a snack.

Then the feeder almost emptied very quickly. We spotted a group of starlings mobbing around the feeder. This was not part of the plan.

We have now moved the feeder inside the garage, by the window where we can see it. The robins are feeding from it.

We are assuming that as both robins are in and out like a fiddler's elbow that they have hatched a brood and are busy feeding them.

We also assume that dried meal worms may not suit robin chicks.

What should we provide to aid the feeding of the chicks?

Is it safe to assume that as the adults are happy flying in and out of the window, and that there is plenty of air space in the garage, that the chicks should fledge then copy the adults in flying in and out of the window?