A PPM Tool is particularly helpful with regards to change requests and change management in general because:

		A PPM tool can help accelerate the copy/paste operation of the change across projects.
		It helps a PPM manager understand how a change in one project could affect one or more other projects
		The changes are by definition larger and potentially dangerous
		"The PPM Tool, through its collborative communication, can guarantee that all team members are updated"

Resource Engagement is facilitated in a PPM Tool as a sort of negotiation bewtween:

		Project Manager and Resource Manager
		Portfolio Manager and Sponsor
		Project Manager and CFO
		Portfolio Manager and Project Manager