[Carriola]

Thank you, you were very kind to answer me. Unfortunately, however, I don't think the solutions work. From the addon channel with SendAddonMessage(MyChannelAddon_channel, msg, "WHISPER", sender) I receive the profession link of the other guildmate For example [Tailoring]. I have to put this link on a frame that collects all the links that I receive from other guildmate.

For now the only way I've found is to put a chat frame on the frame (see screen):

function LaFratellanza_Prof_ChatFrame_Init()
    local background = CreateFrame("Frame", "LaFratellanza_ChatFrame_Backgroud", LaFratellanza_main_frame);
    background:SetSize(256, 256);
    background:SetPoint("LEFT", LaFratellanza_main_frame, "TOPRIGHT", -15, -150);
    background:SetBackdrop({
        bgFile = "Interface\\AddOns\\LaFratellanza\\texture\\frames\\finestra-laterale.tga",
        tile = false,
        insets = { left = 0, right = 0, top = 0, bottom = 0 }
    });
    background:SetFrameLevel(LaFratellanza_main_frame:GetFrameLevel()-1);

    LaFratellanza_chatFrame = FCF_OpenNewWindow("LaFratellanzaProfessioni");
    LaFratellanza_chatFrameTab = _G["ChatFrame" .. LaFratellanza_chatFrame:GetID() .. "Tab"];
    LaFratellanza_chatFrameButtonFrame = _G["ChatFrame" .. LaFratellanza_chatFrame:GetID() .. "ButtonFrame"];
    LaFratellanza_chatFrameEditBox = _G["ChatFrame" .. LaFratellanza_chatFrame:GetID() .. "EditBox"];

    ChatFrame_RemoveAllMessageGroups(LaFratellanza_chatFrame);
    ChatFrame_AddMessageGroup(LaFratellanza_chatFrame, "ADDON");
    
    LaFratellanza_chatFrame:SetScript("OnEvent", function(self, event, prefix, message)
        if event == "CHAT_MSG_ADDON" and prefix == LaFratellanza_channel then
            if string.sub(message, 1, 3) == "Res" then
                self:AddMessage(string.sub(message, 5))
            end
        end
    end)
    LaFratellanza_chatFrame:RegisterEvent("CHAT_MSG_ADDON");  
	CURRENT_CHAT_FRAME_ID = LaFratellanza_chatFrame:GetID();
	FCF_ToggleLock();
	LaFratellanza_chatFrame:SetParent(_G["LaFratellanza_Main_Frame"]);
    LaFratellanza_chatFrameTab:SetParent(_G["LaFratellanza_Main_Frame"]);
    LaFratellanza_chatFrameButtonFrame:SetParent(_G["LaFratellanza_Main_Frame"]);
    LaFratellanza_chatFrameEditBox:SetParent(_G["LaFratellanza_Main_Frame"]);

	LaFratellanza_chatFrame:ClearAllPoints();
	LaFratellanza_chatFrame:SetFrameLevel(_G["LaFratellanza_Main_Frame"]:GetFrameLevel()-1);
	LaFratellanza_chatFrame:SetWidth(220);
	LaFratellanza_chatFrame:SetHeight(180);
	LaFratellanza_chatFrame:SetPoint("TOPLEFT", _G["LaFratellanza_Main_Frame"],"TOPRIGHT", 10, -70);

    LaFratellanza_chatFrameButtonFrame:SetWidth(0);
	LaFratellanza_chatFrameButtonFrame:SetHeight(0);
    LaFratellanza_chatFrameButtonFrame:ClearAllPoints();
    LaFratellanza_chatFrameButtonFrame:SetPoint("TOPRIGHT", UIParent,"TOPRIGHT", 0, 0);
    LaFratellanza_chatFrameButtonFrame:SetFrameLevel(_G["LaFratellanza_Main_Frame"]:GetFrameLevel()-1);

    LaFratellanza_chatFrameEditBox:ClearAllPoints();
    LaFratellanza_chatFrameEditBox:SetWidth(20);
    LaFratellanza_chatFrameEditBox:SetHeight(20);
    LaFratellanza_chatFrameButtonFrame:SetPoint("TOPRIGHT", UIParent,"TOPRIGHT", 0, 0);

    FCF_SetLocked( LaFratellanza_chatFrame, 1 );
    FCF_SetWindowAlpha( LaFratellanza_chatFrame, 0 );
    LaFratellanza_chatFrame:SetMovable( false );
    LaFratellanza_chatFrame:SetResizable( false );


    local header = CreateFrame("Frame", "LaFratellanza_ChatFrame_Header", LaFratellanza_main_frame);
    header:SetSize(256, 64);
    header:SetPoint("LEFT", LaFratellanza_main_frame, "TOPRIGHT", -15, -55);
    header:SetBackdrop({
        bgFile = "Interface\\AddOns\\LaFratellanza\\texture\\frames\\header-finestra-laterale.tga",
        tile = false,
        insets = { left = 0, right = 0, top = 0, bottom = 0 }
    });
    header:SetFrameLevel(LaFratellanza_chatFrameTab:GetFrameLevel()+10);

    local headerTitle = header:CreateFontString(nil, "OVERLAY", "GameFontNormal");
    headerTitle:SetPoint("TOPLEFT", header, "TOPLEFT", 30, -30);
    headerTitle:SetText("LINK PROFESSIONI");
end

screen: https://ibb.co/GxWJcMb

but unfortunately I find chat frames unpredictable. Sometimes it disappears for no reason and i can't really hide ButtonFrame, EditBox and tab of the chat.
I will try to find another way, thank you very much!

You have been very kind!