Feels...
Hope your daughter gets better soon.
I agree that if there's no known contact with an existing carrier then it is likely that she does not have COVID19. Regardless, flu symptom treatment is essentially the same as COVID19 symptom treatment.
The US CDC has a article that suggests the "secondary attack rate", i.e. the rate at which close contact transmission occurs, is 10-20%. So it is definitely not a foregone conclusion that the rest of the family would catch it.
https://www.cdc.gov/mmwr/volumes/69/...cid=mm6909e1_w
Since this strain is "novel", meaning that there is no likely large scale population immunity, and that there will not be a vaccine available for 12-18+ months, the fact is that the strain will likely continue through to the population until the magic "herd immunity" is achieved.
I have read that the four other strains of coronaviruses that affect humans do actually result in post recovery immunity, but that it is not assured with this strain as the data is not in yet. I understand that experts believe that post recovery immunity is likely for at least some time (years?).
The majority risk factor seem to be age (65+), current smoking history, compromised immune system, and/or other existing medical issues such as emphysema. So seems like the risk of serious complications is low or very low (especially for the young).
Is it better to get it now? Maybe... You could develop immunity, and if in the unlikely event that you do develop complications, the availability of ICU space where you are is probably good for now. OTOH, maybe the ICU units are still figuring out their process and systems currently, so perhaps "waiting" 45-60 days would be better...
It is unlikely you will "be able to get back to life" until the "herd" also catches up...
Might be best to wait until summer is over in two weeks so you can still get your beach days in.
Seriously though... Hope she feels better soon. Fluids, vit.C, and pediatric acetomenephen.