You can get both diagonals of the quadrilateral:
PR = sqrt(10^2 + 3^2) = sqrt(109)
QS = sqrt(10^2 + 4^2) = sqrt(116)
However, nothing seems to prevent point S from coinciding with point D, and point R with point C.
So, re-naming the square ABRS, then quadrilateral has sides PS = 3, RS = 10 and:
QP^2 = AP^2 + AQ^2 = 7^2 + 4^2 = 65; QP = sqrt(65)
QR^2 = BR^2 + BQ^2 = 10^2 + 6^2 = 136; QR = sqrt(136)
Perimeter of quadrilateral PQRS = 13 + sqrt(65) + sqrt(136)
Well, any attempt is better than none!
EDIT:
had another look at above idea: results in same area for the quadrilaterals,
but not same perimeter.
C'mon Loch, we need MORE INFO :shock:
In case interested; smallest case where the quad's sides are all integers and different:
square sides = 108
triangle APQ: 60-63-87
triangle BRQ: 48-90-102
triangle CRS: 18-80-82
triangle DPS: 28-45-53
Last numbers (87,102,82,53) are the quad's sides.