Each school will look at all their applications and draw up a
rank order based on their oversubscription criteria to decide
who will get places. Oversubscription criteria are a set of rules
which a school uses to place children into priority order, or
rank, if it receives too many requests for the places that it has
available. This means, for example, that if how close children
live to the school is an important factor, the children who live
closest are most likely to be offered places.
The order you name the schools in only matters if more than
one of them could offer your child a place. If this happens,
we will look back at your preferences and offer whichever of
them you named highest on the form. The unused offer for
the lower preference school(s) will then be offered to a child
that was ranked lower on that school’s list.

Piggybacking the thread with a different SCAF question, sorry. If you're offered a lower preference and accept, while going on the waiting list for a higher one, you're not obliged to accept if an offer from the higher one eventually comes through, are you? Presumably you have a week or so to accept/ decline as with the original offer, so if circumstances have changed you can keep the place you first accepted?

Please check with your own LA as to how waiting list offers are handled. At least until recently, there was at least one LA (possibly Herts?) which automatically replaced the place held with the new place. Most LAs have you a few days to decide, though, I think.