I assume you'll be appealing against non-qualification and oversubscription, in which case you'll need
(a) academic evidence
http://www.elevenplusexams.co.uk/11plus ... rs.php#b11
(b) extenuating circumstances
http://www.elevenplusexams.co.uk/11plus ... rs.php#b10
and (c) reasons for this particular school
http://www.elevenplusexams.co.uk/11plus ... ers.php#c2
would it be correct to mention my older son
It's worth mentioning that there's a sibling at the school under (c) above, but the other points ("he only just scraped in" but is doing well) won't carry any weight.
when the younger sat the test things were difficult with a very absent father (had not seen for 2 years) dragging us through court
Worth a mention under (b) above, but it would carry more weight if (1) there is evidence that school work also suffered at that point in time, and (2) you alerted the headteacher about the problem.
i feel with a bit more of a push at a grammar would benfit him greatly should i mention things like this?
There is a bit of advice about setting out an appeal here:
http://www.elevenplusexams.co.uk/11plus ... rs.php#e11