Mounting Multiple host directories + Memory provisioning

[Sorcerer Stone]

My OS is windows. Running Vagrant on Virtualbox.
I am trying to run a number of docker projects in such environments.
I created a Vagrantfile.
Inside the loop for: Vagrant.configure("2") do |config|
I have:

config.vm.synced_folder "./local_dockerproject1", "/commonbase/local_dockerproject1"

Inside the above local_dockerproject1 directory on the windows host, I have the compose.yml file for project1.

All is well. The host folder is mounted into the virtual machine environment and I can run the docker container.

I want to run more projects within the same environment (Vagrant + Virtualbox)

Each projects has its own compose.yml file sitting in its own directory.

Is it possible to chain link additional host folders like below:

config.vm.synced_folder "./local_dockerproject1", "/commonbase/local_dockerproject1"
config.vm.synced_folder "./local_dockerproject2", "/commonbase/local_dockerproject2"
…

If the above is possible, say I have 4~5 projects running simultaneously in this setup. What kind of RAM allocation I should assign? Right now, with 1 project, I assigned 4MB RAM (My window host has 8GB RAM) as follows:

config.vm.provider "virtualbox" do |v|
  v.memory = 4096

Can Vagrant automatically request more RAM allocation from the host if Vagrant, the virtual machine manager, runs low on memory? Or I have to manually provision the RAM allocation and restart the Vagrant engine again?

Thanks in advance.
Sorcerer