How do you anchor tons of groups with a script?

I've been working for so long on a new map spawning in a lot of pine trees. After all my work I noticed the objects in the pine trees weren't anchored I made a group of all the pine trees called "PineTrees" inside there I put a normal script to try to anchor all the objects in the groups. It ended up throwing the error "GetDescendant is not a valid member of Model". Here's the script:

local model = script.Parent
	local childs = model:GetDescendant() 
for I,v in pairs(childs) do 
    if v:IsA("BasePart") then 
        v.Anchored = true
    end
end

I believe the function you are looking for is :GetChildren() It will find all the children.