This is an interesting article in Entrepreneur which is US based but the tips here ring true for companies based in England and Wales as well.

The key thing is to plan ahead (pre/post nuptial agreements can be indispensable) and (as hard as it may be) try to keep your emotions in check for the sake of the business. Alternate dispute resolution (arbitration/ mediation / collaborative law) can also be an excellent forum for settling disputes over the family business.