What do mean by doubling Kat? When you say splitting at the free edge do you mean splits at the sides of the nail? this would be the stress area.... if this is happening then your nails are not supple enough so do not take knocks too well...... plenty of solar oil for a start... my index finger and thumbs are like this and it drives me mad!!
Wearing enamel or an overlay will help to protect too.
It is strange when we all have different ways of describing things. Do you mean peeling where the nail seems to come off in layers? This can be due to dryness of the nail and constant over wetting and then drying out. Solaroil or a good grade cuticle oil massaged in regularly will help this over time. Also do not over file the nails as this can cause the layers to split. Gentle side to side motion with a high grit file - nothing lower than a 240. Also keep them covered with a good treatment basecoat, colour and top coat and also seal the free edge when varnishing.