Is Pact of Succession Recognized in Roman Law?

Present study is dealing with possibility of pact of succession in Roman law. Traditionally, there are only two grounds for succession recognized in Roman law – the testamentary succession and the intestate one. Combining of the two grounds was not possible apart from the military will (testamentum militis). The military wills were privileged in many ways – there were not many formal requirements, therefore the soldiers were able to make a valid will in any way they can or want to.
Despite not being widely recognized, there is a way even a pact of succession can be valid – via military will, that can contain miscellaneous provisions and there is nothing barring an agreement with features of pact of succession. This idea appears in the age of Roman law reception, when doctores were searching for Roman-law-based solution, that would support pacts of succession between aristocratic houses.