If you are telling that to someone exactly at the same moment when you’re having breakfast you should say “I am having breakfast with my mother”. “I have breakfast with my mother” can be used when you are talking about your daily activities, for example: “Every morning around 10 o’clock I have breakfast with my mother/friend.” Example 2: “I have lunch with my sister on the weekends”. I hope it helps!

“I have dinner”, etc. is more habitual. E.g. I have dinner with my mom on Mondays. Otherwise, you would say, “I am having” or “I had...”

It should simply be I (HAD) dinner/breakfast/lunch/ with my father. This is simply because the action was in the past. +233550271318 whatsapp me for more help if you want. Thanks!