Can you please clarify if the issues only pertain when one relative is called up immediately after another relative or even if there are other aliyot between the two?
The reason that we don’t call up two relatives consecutively is because of ayin hora. It only applies if the two aliyos are consecutive, and not if there is someone else that got an ayila in between. as aside point if the tow aliyos are shviei and maftir and they are in two separate sifrei torah then it is permitted, because that it enough of a separation and not considered on after the other.
O:CH 141-5, M:B 20.