I have a bit of a problem at least performing to family, that when I go to place two sponge balls in their hand, they recognise that they are being given two...is it the size of them or simply performance error?

Are you compressing them together, prior to the load? Also, it is sometimes a good idea to guide their hand...helping them to clench around the sponges. Assist them in turning their hand palm down, afterwards. This will make it a little more difficult for them to prematurely open their hand and discover the extra sponge. Once their hand is in the palm down position...you'll be able to notice if they start to turn their palm upwards. Quickly remind them to keep their hand palm down. It's really all about audience management. Learn to control the situation.

Try to work your routine for more than one person. Don't let a "one ball" person handle two balls. That way they won't have any point of reference and won't know how they're supposed to feel.

Thanks for the tips guys.

Jonah