Nothing wrong with that soil or its nutrient content as far as supplying sufficient nutrients for a healthy lawn.

Color may be improved by increasing iron levels and lowering pH towards mid 6's. Easiest method of lowering pH over time is through the use of synthetic N like ammonium sulfate or sulfur coated (slow release) urea. Iron can be supplied using Milorganite or another supplement like Ferrous sulfate or Ironite. Milo will also supply phosphorous. Milo or an application of starter fertilizer to increase phosphorous will create more of a buffer/reserve and possibly slightly improved Spring root and rhizome (if KBG) growth.

Two things. First, what are the complaints. Second, what about the things that don't show up in a soil test? Compaction, traffic, shade, water?

Good questions, wayned. In addition, where does the in-law live?

What is the in-law's watering schedule? How often and for how long?

Pictures are worth thousands of words. The best time to take garden pictures is on a cloudy or overcast day. Being a lawn problem it is usually good to get a picture from the street and one from 6 inches away.