With this setup:
Form1
tabControl1
tab1
tab2
Form2
button1
textbox1
Is it possible to add Form2 to tab 2? So if I were to click on tab2, Form2 would show up within that tab?
"@Idle_Mind Nailed it, thank you. – Blankdud"
It's possible by setting the TopLevel property of your Form2 instance to false at run-time, and then adding it to the TabPage controls collection before calling Show(). Note, however, that controls displayed in forms this way do not behave correctly with respect to tabbing. Use a UserControl instead of a form.