WTF? if she feels that strongly about it you have two options...provide sposies for when bubs stays at your mums
or say, this is my child, if youre not willing to care for her without performing necessities (e.g.nappy changing), then you cant babysit! she cant want to babysit but refuse to change nappies, wtf that makes me angry!! although im gonna be using sposies and i commend you for using cloth! *clap*