cannot add exisiting flow to solution

[mmchx]

I add the existing flow to the solution, but some of my flow disappear both in "From Dataverse" & "Outside Dataverse".

How can I add that flow to the solution?

and additional questions

1.  after adding the flow to the flow, it will disappear from "My flows" and  "shared with me" right?  so, if flow A I have 2 owners,

if I add flow A to solution A, another owner will see flow A in the solution, right? and can I make it appears on "my flow" / "shared with me"

2. I have noticed that after I remove some flow out of the solution, that flow will move to "From Dataverse".

• so what is the difference between From dataverse vs outside?
• Can I move it back to outside dataverse?