I don't thin this will work to avoid rule violation
it is one receiver (or something like a PC using PCIe-cards) with 3 multiple-tuner
even one multiple tuner itself (sounds like FBC tuner) might receive more than one program, even more than 2 channels at a time - and he has 3 of this multi-tuner-boards in his one device
you might setup several readers with different account names (one dual-login and one single-login) but how to tell Oscam (or which emu ever is used, not specified here) to use "the second reader/account-name" ?
as long as the 1st reader for the CAID is working, Oscam (or Mgcamd, or CCcam) will send requests for 10 or more channels to the same reader/cs-line as long as this reader respond with codewords, even fallback-configuration will not help (fallback will help to switch to the 2d user-account/reader once the 1st account is blocked because of rule violation:))
I think he has to configure the receiver to use only 2 tuners enabled at all and disabled FBC/multi-tuner-function on this receiver to use a dual-login account (or disable two of the 3 tuners and even switch of FBC function on the remaining single tuner while using a single cs-account)
it might work using CCcam protocol within Oscam and configure load balancing to avoid to many cw-requests (also depends on the subscribed package)
I have tried to configure load balancing myself because as soon as a channel is not decoded and Oscam get the respond "not found" it send out directly a 2nd (and 3rd and 4th...) request to decode the channel if you switch to a channel that cannot be decoded (regardless of not in subscription or cs-server error) - and I have not found an option to disable this behavior. This has nothing to do with timeout settings as there is no timeout, the server respond with "not found" so Oscam is going to try again. Even if this ends in a rule violation message, its not a problem, next day its gone.
But if you configure Oscam to send only lets say 8 requests per minute and the tuners are receiving to many coded channels = tries to decode this multiple channels, Oscam does not know which of this cw-requests are for the active tuner you are using to watch TV and which cw-requests are for the channels received in background = most likely the blocked cw-request by load balancing will be the one you receive on TV or record, at least from time to time = freezers.
However, the limitations of the cs-server are known: one channel for single tuner with ordinary cs-account, or dual login for twin-tuner, there is no option of triple-login and 3 or even more tuners/cw-requests. If you need to receive 3 channels at a time you need to split to 2 receivers and as suma described use a dual-login on a twin-receiver(2 PCIe tuner cards) and another cs-subscription for single-user on another single tuner device - and disable FBC-function/multi-tuner-feature