Even though my upcoming vaction is just one week not one month of it, I'd like you to regard it as one month and read my story.

Of coure, I will apply the  assumption that I don't need to worry about money or work to this story alike.

1) What place will you visit first?

I will go to Swiss (Switzerland) which (where) my relatives live in and stay there for 4 days and then transfer to Germany.

While we stay in Swiss (Switzerland), we will go sightseeing in (the) Alps and other beautiful sites.

I'm sure that my relatives will escort and accompany us no matter where we go.

(For your reference, my relatives are (the) one son and two daughters of my aunt. My aunt is the elder sister of my father. Unfortunately she passed away due to  cancer several years ago. (Her) son's name of my aunt is Mark and (her) two daughters' names of her are Claire and Liz each)

2) What will you pack for your journey?

Since I'm sensitive and picky to (with) almost everything, I will bring (a) first-aid-kit, comfortable shoes, sunglasses and so on.

3) Who will you see?

Of course, the main purpose of this trip is to meet my blood ties in person and introduce my wife to them for the first time.

I believe that it will be a good experience for both of us and from this chance, the blood relationship between us and them will be more active and intimate.

**Honestly, nice writing.  I think you are improving so much and now we just need to focus on getting some of the articles right (the, a, an) and making your writing more natural to a native speaker.  :)