[Baertram]

You can always call the "widget" functions of LAM controls directly in your lua code to e.g. create a LAM dropdown or checkbox somewhere else, not in a LAM panel, afaik, using the function that the widget uses itsself:

LAMCreateControl

But I'm not sure if this will work for all controls of LAM. You'd have to test this.
I guess it would work though.

At the bottom of each widget lua file you will find the name of the control that is created, e.g. for a slider

LAMCreateControl.slider(container, data, name)

Similar for a submenu then:

function LAMCreateControl.submenu(parent, submenuData, controlName)

The function returns the created container of the control then.


Edit:
You need to get the rank of a guildMemberIndex
and then check if the rank got a guildmaster.
IsGuildRankGuildMaster(guildId, guildRank)

Here is an example code, !!!untested!!!

--returns nilable:String nameofGuildMaster, nilable:number memberIndexOfGuildMaster
local function getGuildMasterData(guildId)
    local isPlayerGuildMaster = IsPlayerGuildMaster(guildId)
    ---Player is not guild master, so search the guild master
    if not isPlayerGuildMaster then
        local numGuildMembers = GetNumGuildMembers(guildId)
        for memberIndex=1, numGuildMembers, 1 do
            --- @return name string, note string, rankIndex luaindex, playerStatus [PlayerStatus|#PlayerStatus], secsSinceLogoff integer
--->Hint: Not sure if name is the character name or the @displayName (account) here, so test this and use accoridngly to your needs
            local name, _, rankIndex = GetGuildMemberInfo(guildId, memberIndex)
            if rankIndex ~= nil then
                local isGuildMemberRankGuildMaster = IsGuildRankGuildMaster(guildId, rankIndex)
                if isGuildMemberRankGuildMaster == true then return name, memberIndex end
            end
        end
    else
        --Player is guild master
        local accountName = GetDisplayName()
        local memberIndex = GetGuildMemberIndexFromDisplayName(guildId, accountName)
        if memberIndex ~= nil then
            return accountName, memberIndex
        end
    end
    return nil, nil
end