Habebe nursing chair - replacement covers

[greentshirt]

Just wondering if any of the bright amongst us have successfully replaced the cushion covers on one of these chairs? I bought a 2nd hand one which is in great condition but would like to change the covers to match colours in baby's room. Have got someone who can make them for me but to save time, does anyone know if the cushion cover dimensions are easily available? Otherwise it's going to be a bit of a faff having no cushions while I wait for her to measure and sort material out etc. I'm already well attached to this chair, want to still use it while I wait if poss!!

Any help much appreciated!