Disease isn’t an issue in ovo, but lockdown could be interesting, are you hand turning? I wouldn’t worry too much about humidity (until lockdown), quail are ‘traditionally’ 45 percent (what are chickens?) unless you are doing dry hatch. The hard part would be turning chicken eggs while in lockdown on the quail. You’ll also want to sanitize the chicken eggs (with a commercial egg sanitizer) before putting them in an incubator where baby quail will be in contact (newborns are very susceptible to disease and egg shells are a great source of bugs and bacteria love warm moist environments (incubator!). The quail will have some resistance to bugs on their own eggs but chicken eggs from a different source are bad news. Between the lockdown issues and novel bugs, it isn’t a great idea unless you can do lockdown separately, then you could incubate for a few days together without issue.