Kitty - Parents are like that... did your parents try to help you after you broke down? If they do, then at least there is progress. Parents are always a bit tricky to handle.
Can I suggest the following? Instead of asking them to give their relatives and friends names. Ask them to tell you how many are coming from each group of friend (eg. Dad's friends - XX persons, Mum's friends - YY persons etc), then in your spreadsheet, you just allocate them table according to the number of persons they told you they invited.
I had 3 tables of dad's classmates. On my spreadsheet, they are all called "Classmate". I told my jiemeis who are at the reception, if you cannot find the name, just ask if they are my dad's classmates. Once confirmed, just tell them the general table number (oh, the classmates are all sitting in tables 28, 29, 30) and direct them to your parents so that they can congratulate your parents etc. This way you kinda have some control on your seating arrangement and your parents also feel a little happy.
I think this worked pretty well for my dad, cuz my dad feels in charge of his guest list, he knows who is coming who isn't. He can update me readily on the people who has arrived and he can even tell me down to each exact guest who gave which angpow and how much.
For relatives, I think in general, you roughly know who among the relatives is coming? If they cannot give you who is coming, then you just ask them down the list "Oh, is 三姨 coming? She's coming ah, then is (somebody related to 三姨) coming as well etc." If they unwilling to tell you then you have to ask/probe lor.
In my guest list, for all my parents' guests, I didn't put names at all. I just wrote on the guest list based on how I address them, whether by their title (eg. 舅妈,外婆 etc) or by names if they are the same generation as me. Chances are, with relatives, they are likely to look for your parents or other relatives first before going to the reception table.
If your parents are not helping you, can you ask your hubby to help you ask them? Maybe they may feel a little more inclined to be more polite with your hubby than to brush him aside like what they did with you. Similarly, you should ask your hubby to check with his parents or your in laws for the guest list, if you haven't done so. THis will take a load off you too.
Don't stress kay? Everything can be sorted.