DS14 has several trips booked this year, and his passport is up for renewal at the end of October. He will be away in April, then away again early July for 7-10 days (France), then another 7-10 day trip to France at the end of August. I think he needs at least 3 months on his passport to enter France, which presents an issue for the August trip. I'm concerned there won't be enough time between the two French trips to risk a renewal (will be about 1 month in between the 2).
Which leaves trying for a renewal between returning from his trip in April, and the next trip early July (giving 2 and a bit clear months). But is this too far in advance (effectively he'll lose 4-5 months of passport time as well, since you can't add on anymore)?