DD is 4 and on a nice day like today has a habit of taking her knickers off, usually followed by her clothes - she just doesn't like the feel of them. MIL is 80-going-on-100 and just keeps on and on about how she should wear knickers and it's "disgusting"... I don't want to make a big deal of it to DD - she's only little still and so what if she's a nudist! What can I say to MIL instead of "just get over it", which is what I usually end up saying, and not very conducive to good family relations?