Instead of burning the miles, I would also look at alternatives to prevent them from expiring:
A) I would try to pool the miles within the family if that is possible. (i.e. if it's your children's miles which expire, then yes, if it's your parents or other relatives, maybe not so easy, but it does say "friends" in the terms, which does seem to leave some room as to whom you can pool with)
An important advantage of the pool is that whoever in your mileage pool is using miles will always use up the miles which expire first. (At least, that is my experience)
B) If the person in question is an adult, then why not apply for a credit card to avoid the miles from expiring?
C) Upgrade C > F for SIN-ZRH will be at least 60k miles per person. Not sure if you meant to upgrade "them" as in "more than one person" travelling.
It would at least use a bit more more than 50k, if LX is releasing upgrades to F.
D) Is reaching FTL out of reach? - That would solve the problem, too.
E) I found that there are still sometimes awards to be had at relatively short notice (1-2 months out) to places one might really like to go.
For example, we found some business award seats to Japan last summer for the whole family, which I found to be a good value vs. using cash.
A few years ago, we got business awards to the US west coast in the middle of the school holidays in fall.