Best strategies to get foreign parents to Japan permanently?

I’m aware this is going to be challenging. I wonder if anyone would have insight or some previous experiences they could share.

Situation: I have lived in Japan for a couple decades (tech industry job). I’m on a Highly Skilled Professional Visa Level 2, married to a Japanese national with a newborn baby. I want to get both my parents (70+, from a very friendly country to Japan) in Japan permanently. My plan is to apply for a Designated Activities Visa for them to support my child until 7 years old. My permanent residency was recently accepted, but am delaying it while I apply for my parents’ visa this month, as PR doesn’t seem to allow for that option. (I’m not sure yet how the Immigration Bureau will react when I’ll submit the application for my parents.) The Designated Activities Visa is likely to work, but I wonder what’s my best course of action afterwards.

Question 1: What are the best strategies for my parents to get to stay permanently in Japan? Does anyone have experiences or stories to share? My parents have previously obtained a Designated Activities visa before. We have then interrupted that visa. Now, because my parents are getting older, I am growing increasingly worried that their health might soon deteriorate. I would like to have them closeby to be able to take care of them as well as possible as that haplens, which means bringing them here in Japan. I can’t use the elderly visa for now, as they are happily married and in relatively good health.

Question 2: Since I have received the notice that my PR was ready, can I postpone instead of dropping it, and if so for how long?

Any advice or story welcome! I’m open to try anything.

Edit: I have consulted an immigration lawyer, but their input wasn’t helpful so far and my understanding is they never encountered my situation before or don’t have a strategy they feel comfortable with recommending. They mentioned once the designated activities visa expires we could go for a working visa or a long stay visa but seem to say it’s tricky.