How do I make a "Tameable" Horse?

I am making a game similar to Davidii's Survival 404, I used his game as a base and have made a completely new map, new items, buildings, ect. One of those things I added was a horse AI that moves using something called the "NodeModel" which are basically nodes that the AI animals move to randomly using this script:

wait(3)

local ME = script.Parent
local TORSO = ME.Torso
local STATS = ME.ANIMAL
STATS.HEALTH.Value = STATS.MAXHEALTH.Value

local REGEN = ME:clone()

local NODE_RANGE = 20

local STATE = "WANDER"

function get_random_from_table(tab)
	return tab[math.random(1, #tab)]
end

function get_drop_name()
	local drop = STATS:findFirstChild("DROP")

	return drop.Value
end

function get_nearby_node(torso, range)
	local nodes = game.Workspace.NodeStorage:GetChildren()
	local nearby_nodes = {}

	if range == nil then
		range = NODE_RANGE
	end

	for index, child in pairs(nodes) do
		local distance = (torso.Position - child.Value).magnitude

		if distance < range then
			table.insert(nearby_nodes, child)
		end
	end

	local chosen_node = nil

	if #nearby_nodes < 1 then
		chosen_node = get_nearest_node(TORSO)
	else
		chosen_node = get_random_from_table(nearby_nodes)
	end

	return chosen_node.Value
end

function get_nearest_node(torso)
	local nodes = game.Workspace.NodeStorage:GetChildren()

	local best_node = nodes[1]
	local best_distance = (torso.Position - best_node.Value).magnitude

	for index, child in pairs(nodes) do
		local distance = (torso.Position - child.Value).magnitude

		if distance < best_distance then
			best_distance = distance
			best_node = child
		end
	end

	return best_node
end

function do_move_animal(torso, position, speed)
	position = Vector3.new(position.x, torso.Position.y, position.z)

	local bv = torso.BodyVelocity
	local bg = torso.BodyGyro
	local vector = (position - torso.Position)
	local unit = vector.unit
	local distance = vector.magnitude
	local time = distance / speed
	local direction = torso.Position + unit

	bg.cframe = CFrame.new(torso.Position, direction)
	bv.velocity = unit * speed

	wait(time)

	bv.velocity = Vector3.new(0, 0, 0)
end

function get_nearby_player()
	local players = game.Players:GetChildren()

	local best_distance = 25
	local best_player = nil

	for index, child in pairs(players) do
		local char = child.Character

		if char ~= nil then
			local torso = char.Torso

			local distance = (TORSO.Position - torso.Position).magnitude

			if distance < best_distance then
				best_distance = distance
				best_player = char
			end
		end
	end

	return best_distance, best_player
end

function get_dead()
	local health = STATS.HEALTH.Value
	local y_pos = TORSO.Position.y

	return (health <= 0 or y_pos < 20)
end

function do_die()
	STATE = "DEAD"

	local torso = TORSO:GetChildren()
	local drop = STATS.DROP:GetChildren()

	--change name of torso
	TORSO.Name = get_drop_name()

	--remove all from torso
	for index, child in pairs(torso) do
		child:remove()
	end

	--give drop stuff in Torso
	for index, child in pairs(drop) do
		if child.className == "Script" then
			local new_script = child:clone()
			new_script.Disabled = false
			new_script.Parent = TORSO

			child:remove()
		else
			child.Parent = TORSO
		end
	end

	--put torso outside of char, make it forageable
	TORSO.Parent = game.Workspace
	TORSO.Locked = false

	--"kill" me!
	ME:BreakJoints()

	wait(5)

	--regenerate
	REGEN.Parent = game.Workspace
	REGEN:MakeJoints()

	--remove
	ME:remove()
end

function do_loop()
	if STATE == "WANDER" then
		--acquire a random nearby node
		local node = get_nearby_node(TORSO)

		--move to it
		do_move_animal(TORSO, node, STATS.SPEED.Value)

		--check to see if I'm in danger
		local distance, player = get_nearby_player()

		if distance < 25 then
			STATE = "RUNNING"
		end

		--pause
		wait(math.random(0, 2))
	elseif STATE == "RUNNING" then
		--acquire nearby node
		local node = get_nearby_node(TORSO)

		--move to it - frantically
		do_move_animal(TORSO, node, STATS.SPEED.Value * 2)

		--check to see if I'm no longer in danger, then wander
		local distance, player = get_nearby_player()

		if distance >= 25 then
			STATE = "WANDER"
		end

		--don't pause!
		wait()
	end
end

--secondary health loop, which checks to see if the animal has died
delay(0, function()
	while true do
		if get_dead() then
			do_die()
		end

		wait(1)
	end
end)

--main loop, runs the whole show
while true do
	do_loop()

	wait()
end

(^This script was included to help you understand how the animal moves, this is NOT the script that I plan to use to do what I am trying to do.)

The script uses values inside the model (the AI animal) to make it animated and I think rocket propulsion values are what they are called to keep its body in the right place when moving. (Like BodyVelocity and BodyGyro). That being said, I am trying to make it so that when a brick is placed within a certain range of the AI, the values and everything else other than the actual bricks that make up the horse are removed, and replace them with a different script and some rocket propulsion values that make the horse basically a drive able vehicle (sorry if I explained that badly) I am a fairly new scripter, so I understand scripting, but I don't really know many functions. I'm asking on here to see if someone could not write the script for me, but maybe show me some of the functions I would need to do all of this. If you need me to clarify anything just ask, and thank you so much for any help, because frankly, i'm lost. :)