We have a light lunch of sandwiches or maccaroni or cheese etc (The girls and I), then a main meal at night where we all sit together between 6-6.30. If DH is late, we will eat and then he has his tea later on. I think it is a great time for us all to catch up on the day.

Dh's mother cooks lunch and tea and they don't have sandwiches at all - so DH hates sandwiches for lunch and will rarely have them, which makes it hard for me on weekends - so then I will cook something for him, but we still have sandwiches.

Maybe it is easier for your sister to do it that way and she is not rushed at night cooking a meal and getting kids ready for bed IYKWIM? If we have a roast Lunch on a sunday - then we have a light tea that night, but most of the time it is light lunch + main meal at night. Do whatever you feel is easier.