I don't think you need partners at Confluence. It's safe and self rescue is easy with the huge pool at the bottom.
Union is a tricky place. Eddies are powerful at high water, >800 cfs. This place at high water is actually good practice for Westwater. But, the water is low now so it shouldn't be bad. Union often has kaykers there when the water is up. Not sure about now--it's kind of low.
There may be an underwater trap below the second drop at Union. A swimmer drowned there 1-2 years ago and was apparently underwater for >30 minutes. If you swim, keep your limbs close in.