This ongoing saga at Reliance is tragic: it is one of the very few (less than 5, surely) entirely homegrown, world class corporations from India but it is being hollowed from the inside in this contest for authority.
I think the time-tested "Mother's Law" of "one brother does the division, the other one gets to pick first" is the most straightforward solution. Yes, it will still destroy some value (the whole is indeed greater than the sum of its parts) but it will allow M/s Mukesh and Anil to independently start building off substantial bases once again.
This will not work, of course, if either one or both believe that equality is not a required feature in a settlement. However, "If thy brother wrongs thee, remember not so much his wrong-doing, but more than ever that he is thy brother" (Epictetus; Enchiridion, 43) holds true as a mantra - whether the division is of a few household utensils or a US$20 Bn industrial empire.
Epictetus (A.D. 55?–135?): Greek (Phrygian-born) philosopher who popularized the Stoic ethical doctrine of limiting one's desires, believing that one should act in life as at a banquet by taking a polite portion of all that is offered. Epictetus' main work is the Enchiridion --or "Handbook", while his longer works are known as The Discourses. It is believed that Epictetus did not write these himself, but that they were penned by his pupil, Arrian. (Source: www.answers.com; See here for more details).