My sister is getting married in 2 weeks and today we found out that her future mother in law was extremely generous and wrote a $1000 check directly to the reception hall (after my sister told her that my mother would likely try to not accept the gift). Obviously my mother will thank her with a heart felt note but is that enough? The wedding is pretty traditional with my mom paying for everything except the rehearsal dinner and the wedding party bouquets/boutonnieres (which are being paid for by the groom's parents) so this gift is absolutely lovely and unexpected! The reception budget is 6K so this gift of 1K will allow for some extra special items that we thought we wouldn't have money for which is amazing! Just want to make sure we thank her appropriately, any advice is appreciated! Thank you in advance!