My wife trains in kendo, MJER iaido, & SMR jodo, with dan in each. I teach judo & European fencing, & train in MJER & SMR, also with dan. So while it's not impossible to learn multiple martial arts at the same time, I sure as heck wouldn't advise starting in them simultaneously!
Ken
Ken Goldstein
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Judo Kodansha/MJER Iaido Kodansha/Jodo Oku-iri
Fencing Master/NRA Instructor
"A positive attitude may not solve all your problems, but it'll annoy enough people to be worth the effort."