Efficient way to start multiple shell scripts from single shell script

This is what my code looks like

master_script.sh

#!/bin/bash
chmod +x *
declare -A test=(
    ["echo1"]="sh `pwd`/echo1.sh"
    ["echo2"]="sh `pwd`/echo2.sh"
    ["echo3"]="sh `pwd`/echo3.sh")

log="$base_path"
for var in ${!test[@]}
do
    `${test[$var]} >> $var.log`
    echo "$var Started! :-)"
done

echoX.sh scripts looks like this

#!/bin/bash
while true;do
    echo "This is from Test1"
    #some Code
    echo "Eching the Output"
    #some other code!
    sleep 60
done

The idea is ok, but as you know, the control is waiting at ${test[$var]} >> $var.log. Each echoX.sh is while loop, So the control is waiting to complete!. I want to start ALL scripts

How can I resolve this issue?. NOTE: There are future planings implement features like, staring single script like

./master_script.sh start echo1, --> Will start only echo1

./master_script.sh stop echo1 ---> Will stop only echo1

./master_script.sh start all--> will starts all scripts

So, thats why I followed above procedure.

There are some other thoughts like.(Which don't want to do!)

echox.sh

#!/bin/bash
echo "This is from Test1"
#some Code
echo "Eching the Output"
#some other code!

nohup_echoX.sh

#!bin/bash
while true;do
  ./echoX.sh >> test.log 2>&1 &
done

Then in the mater_script.sh, ill add the ./nohup_echoX.sh in for loop.

So, is there any way to implement this. And more thing, I saw(ps aux | grep <NAME>), there are multiple instances of same process are running. So, how can I control this?