How to do Mediation across pre-post timepoints?

Hi all, I am looking into analyzing potential mediation and not sure how to approach it with two timepoints. For some context, participants are measured at two timepoints: pretreatment (T1) and posttreatment (T2). All participants receive the same treatment. At pre and post, they complete measures for anxiety, attention, and depression. I would like to address the following questions (all variables continuous):

Is change in anxiety from T1 to T2 mediated by attention at T1?

Is change in anxiety from T1 to T2 mediated by change in attention from T1 to T2?

I am thinking difference scores are going to be involved somehow? Any advice on how to proceed would be greatly appreciated!
Cross lagged SEM or Path analysis. Mplus or Lavaan (R). Also, there is a less powerfull ad-on for spss called "Process" that can do part of the analysis (can only do path). Difference scores is gonna need to be a new variable mediating the IV and the DV.