There is of course no one size fits all standard methodology for calculating a settlement range in dispute resolution. In contentious probate, a method which occurred to me, whilst not being scientific, may be practical where liquid assets in the estate (or realisable liquidity) is greater than the sum of the agreed settlement multiplied by the number of beneficiaries (including the claimant), is as follows:

Win = loss of 1/3 costs (unless costs are awarded on the indemnity basis).

If own trial and preparation costs = £50k = £16.6k.

Split (i.e. to demonstrate goodwill) 50:50 = £8.3K.

Lose = £50K x 2 = £100K.

If chances of losing = 25%.

£100K x 25% = £25K.

Therefore BATNA settlement range = £8.3 – £25K. Mid-point = £12.5k.

Each party bears own costs up to settlement.