Upper control arm replacement

It is still connected, should I put the control arm back in place an out a bolt in it to secure it
yes. pop it back in. leave the ball joint castle nut a few threads on and crack it off the spindle. support the lower control arm so it doesn't go flopping all over the place when you take off the nut and pull the upper arm away. namely, watch you don't stretch and bust a brake line.

if you haven't already, pull all the tension off the torsion bars. remember to loosen the lower control arm pivot nut first and only tighten it up once it's back on the ground and your ride height is set.