I think Cathus has got it nailed. Always save at max. quality regardless of any other space saving reductions you might have done. Reducing the ppi to 150 shouldn't result in any overt pixelation unless your relatives are making wallpaper from the jpegs. I am assuming the problem arises when they print the pix not when viewing on screen.
I can't think of anything else you've done which could cause this unless you've overcooked your 'adjustments'
.