Since my question didn't get an answer yet, I post this answer as a possible solution.
What I'll describe is not meant to be the right way to port an answer from SE network, but just a possible right way. So if you feel another approach could work as well, please add an answer here.
Situation on SE network:
Therefore migrating the original question as it is to match one's answer may pose several additional problems.
What I suggest as a possible strategy is to create a brand you question that can match one's answer. At the same time some editing of the answer may also be useful.
All this will improve the Q+A quality as it is posted on CoDidact.
There is a problem, though. Many questions, even if high quality, may not reflect what the answer owner may actually ask and could skew the perception of people looking at his/her Q&A records.
For example, it would seem odd that an EE with years of experience would ask why bypass capacitors are used on digital chips pins.
Therefore it is useful to add a disclaimer text at the beginning of the question. The text could go like this:
Question Migration Disclaimer. This question was purposefully made-up for migrating and matching my subsequent answer, which was originally posted on ElectricalEngineering StackExchange site. This question might be substantially different from the original question, whose author was not me. Any modification and/or addition was performed to improve the quality of the overall Q+A pair.
Then, in the answer, a similar disclaimer would be put:
Answer Migration Disclaimer. This answer was originally posted by me on ElectricalEngineering StackExchange site. This answer might be substantially different from the original answer. Any modification and/or addition was performed to improve the quality of the overall Q+A pair.
In this way we can signal the reader not only that this is not completely new material (he may have already found the older answer using Google), but that this was not plagiarized and that the enhancements where not made to hide such plagiarism.