Can the no-VOC paint by Freshaire be mixed with Glidden's interior flat latex paint? I need to lighten the no-VOC color.
Your best bet is not to mix.
Interestingly, Freshaire and Glidden are owned by the same parent company, ICI. If you look at non-VOC paints, they all have their own special formulations and properties. Many, such as Freshaire, come in set palettes, so I don't think it would be a good idea to mix.
Rather than throwing good money after bad, if you have FreshAire on hand, you can donate it (to a local school theater program, for example) and purchase a new color paint for your home.
For more information:
Read William Fry's Q&A "Is the no-VOC paint Freshaire Choice a good pick for painting my son's room?"