<p>Waiting for someone else step in and provide a complete answer there, when such answers already exist, but in different posts seems unlikely, besides a little bit counterproductive.</p>

<p><strong>Alternatively</strong>, you can accept the answer to your main question, i.e., the question number 1, which is more closely tied with the question's title and; simultaneously edit that accepted answer (or leave a comment beneath it) to include a final sentence in it along the lines:</p>

<blockquote>
  <p>Edit from @Ytsen de Boer (OP): question number 2 is [satisfactorily] answered at @xxx user.</p>
</blockquote>

<p>This way, you can accept one answer and promote upvotes on both answers. Everybody wins.</p>

<hr>

<blockquote>
  <ol>
  <li>Accept one of both? <strong>A: Yes, but make sure to be clear the other answer, answered the second part of the question.</strong></li>
  <li>Have posted 2 questions in 2 posts? <strong>A: Yes, if you had not posted it yet.</strong></li>
  <li>Answer the question myself, borrowing from, and mentioning, the other authors? <strong>A: This is not productive to me; it would compete with the original answers, removing attention/credit/votes from them. If such answers were posted as comments, then, yes.</strong></li>
  <li>Ask the authors of both answers to include their answer to the other question also? <strong>A: No, if they did not answer the other part of the question, it is because they did not want to. Not that asking would hurt, but why ignoring the complementary existing answers?.</strong></li>
  <li>Do nothing? <strong>A: Given the amount of answers received, doing nothing would be quite frustrating.</strong></li>
  <li>Wait for someone to answer both questions in a single answer? <strong>A: Not productive.</strong></li>
  <li>Do something else? <strong>A: Not necessary, option 1 is fine.</strong></li>
  </ol>
</blockquote>
