Hi. Hikvision from eBay and the likes will end up being a waste of money.
Hikvision will not give you any support or supply updates for them to connect to the new hik connect or services plus they are old units on eBay.
With that Costco system you will have the same problem as your dad it will not show full res on 4 display.
Hi. Your monitor is only for viewing .......2-3-4-5mp is size of res stored footage to your hard drive........ it’s your recordings that’s important not the live view.
Take a look at the qvis viper dvr uk based company and it beats the hik and Swann