", with" as a modifier

[TeresaC758]

Below are two correct sentences from the OG:

The Anasazi settlements at Chaco Canyon were built on a spectacular scale, with more than 75 carefully engineered structures, of up to 600 rooms each, were connected by a complex regional system of roads.
Starfish, with anywhere from five to eight arms, have a strong regenerative ability, and if one arm is lost it is quickly replaced, with the animal sometimes overcompensating and growing an extra one or two.

In these two correct sentences above ", with" modifies the preceding subject? (ie: settlements with 75 structures, starfish with arms) However, in the second independent clause what exactly is the phrase ", with the animal sometimes overcompensating" modifying? Is it the entire conditional clause?

Thanks so much!

[Sage Pearce-Higgins]

Please read the forum guidelines before posting. Unfortunately, due to copyright, you're not allowed to post problem from the Official Guide here. Also this looks like a general verbal question, not a problem from the GMAT Prep software.

I agree that 'comma with' modifiers are often confusing and it's a good idea to look at correct examples to see the ways that GMAT uses these modifiers. Rather than looking for a single rule that covers all types, however, I encourage you to be aware that there are multiple ways that GMAT uses 'comma with' modifiers (as your examples show).

The 'starfish, with...' is a noun modifier.
The 'spectacular scale, with' is, I would say, an adverbial modifier. It seems to explain the spectacular scale that the settlements were built on. By the way, I'm pretty sure that you've copied the second part of this sentence incorrectly.
The 'replaced, with the animal' is an adverbial modifier called an absolute phrase. Check out chapter 10 of the SC guide for more on this.

However, the good news is that I've very rarely seen 'comma with' modifiers tested on SC problems - there's almost always some other split that's easier to deal with.