Recruited after an open nationwide search, the new trustees will join the 22-strong board that is set to replace the legion's national council and take responsibility for decision-making and governance.
The day-to-day management of the legion, meanwhile, will be delegated to the executive group.
The restructure is the latest step in the Royal British Legion's seven-year modernisation programme, which has been aimed at bolstering income in an era of flagging support for ex-services charities.
Public opposition to the wars in Iraq and Afghanistan and the declining number of Second World War veterans pose challenges common to all ex-forces charities, and the legion has stated that it wants to be an example of best practice for the entire ex-forces sector.
Since last week's annual conference in Torquay, at which the new model was announced, responsibility for the membership body has been passed to a new membership council. This will be chaired by a trustee and consist of 10 elected county chairmen.
In another change, delegates voted by a two-thirds majority to bring in a new single class of membership. It is hoped that this will encourage greater involvement of members with no service experience.
The legion is also seeking more input from relevant bodies, such as the Ministry of Defence and other ex-service charities, in a new advisory assembly that will meet at least once a year.
This is widely expected to pave the way for the creation of one 'super charity' for all the UK's ex-military personnel. The legion has already initiated talks with SSAFA Forces Help about a possible merger.
Brigadier Ian Townsend, secretary general for the Royal British Legion, said: "This is a turning point in the history of the legion."