New mother taking older kittens in her birthing den

Our Cat Freddie Had kittens 7 weeks ago, they are running around and their mom is not unattentive but trying to ween them off.  In the meantime our second cat "Felix" , The DAY she was about to gave birth, grabbed one of Freddie's kittens and tried to drag it into her birthing chamber ( a little box lined with towels we set up for her) to milk him!  A few hours later we discovered all three 7 week old kittens nursing on Felix just hours before she gave birth to 4 beautiful kittens of her own.  Even after giving birth she is STILL trying to drag the older kittens into her little den.  It must be natural, however, we have never seen anything like this! lol.  Any advice or shared experiences?........

You may need to put the new mama and her newborns in a separate room so she can't get to the older kittens and they cannot get to her. The mama's milk needs to go strictly to the newborns who cannot eat any other way. Put mama's food, water, and litter in the room with her, and keep the older kittens out. They really should not nurse from her at all.