Most all travel insurance policies may be modified up to the day prior to your departure.  Make sure that you request and receive revised policy documentation reflecting any requested changes. 

Related articles:

• How late can I change my travel dates for my travel insurance plan?
• Can travel insurance be purchased after I have departed for my trip?
• I purchased travel insurance and my trip costs have unexpectedly exceeded the insured amount? What should I do?
• If I purchase travel insurance online, how will proof of the insurance be sent to me?
• If I purchase travel insurance for my trip and my trip changes, may I still use the same travel insurance policy?