relationships between 3 entities in ER diagram--is a ternary enough or are 2 binaries also needed?

I'm trying to draw an ER diagram for my project management software describing the following. It contains these entities:

• project - software projects
• tasks - software projects that can be broken into a number of tasks
• employees - employees that belong to this software

And:

1. A project can be divided into tasks. (Tasks can be created by the admin user, who can assign those tasks to selected projects. Here there is only assignment of tasks to projects, not assignment of employees to projects.)

2. Employees can be assigned to projects.
   (An employee can be assigned to projects. Here there is only assignment of employees to projects, not assignment to tasks of projects.)

3. For a selected task of a selected project we can assign employees from the pool--employees that are assigned to that project in 2. (This time we must specify project, task & employee; all 3 selections are mandatory.)

The input processes for 1, 2 & 3 above can be done in separate pages in the system. You can select any of them first.

For the above relationships I created this ERD:

Consider

• relationship 1 between project and task
• relationship 2 between project and employee

Is there a need for the two separate relationships as in the ER diagram, relationship no 1 & relationship no 2?

or

can we use only relationship 3 among project, employee and task, relationship no 3, for that also?