in denmark most Dyner is 70*100, i havent had any problems with it being that big, i just wraped it around my baby when she was small, så half under her and half over her, in the sommertime i just put her on top of the dyne, that was enough and then a planket over her.
i personally havent seen smaller dyner, but you could buy a big one and then cut it in half and sow it togehter, then the problem would be finding a cover that fits.
i apologise for my written english. If any misspellings then too bad :)
Anmeld