Not sure if we are going to appeal now. We would lose our place at Balcarras if we did that with no guarantee that we would get in at Denmark Road (good chance, but not definite). We only got into Balcarras by the skin of our teeth (.99 of a mile!!) so not sure what we're going to do. DD has had enough of the uncertainty and since we wouldn't know outcome till June/July, really not a pleasant prospect.
There's no need for Balcarras to know that you're appealing to another school - unless you tell them , and you're under no obligation to do so.
If I were you, I'd accept the place at Balcarras, then put in the appeal for High School. If you win the appeal, then you can turn down the place at Balcarras (freeing it up for a delighted person on the waiting list), or if not, you still have a place there.
The only down side is that you can't buy the school uniform until the appeal results are out, bit think of it this way - you buy them now and your daughter will have grown out of them come September.