Is there any way to link these two clauses? (I overthought it, so my brain suddenly went blank)

(in these examples: Amy is a child going on a trip, accompanied by two families of friends who are also going on the trip)

Two other families were also going on this trip. The parents agreed to look after Amy.

Can you link them like this, using 'in which'?

Two other families were also going on this trip, in which the parents agreed to look after Amy.

On this trip, the other travelling families' parents agreed to look after Amy.

Do any of these make sense? Does the third one do a bad job of introducing? If yes, how can I improve it? Any help would be appreciated!

• Who is Amy? Is Amy going on the trip? Is Amy a child or a parent, or both? Are Amy's parents and or children going on the trip? What is the relationship of Amy to the two other families?
– user6951
Jan 7, 2015 at 1:43
• By the way, it's usually best to wait 24 hours before accepting an answer, even if you get a good one right away. More info is here. Jan 7, 2015 at 2:28

Depending on what you actually want to say, you can connect the two independent clauses in any number of ways.

As you suggested works adequately, making the second a relative clause :

Two other families were also going on this trip, in which the parents agreed to look after Amy.

Making a time connection with while makes the second a dependent clause:

Two other families were also going on this trip, while the parents agreed to look after Amy.

You could choose any other subordinating conjunction from the list of common ones below to fit your meaning:

after, although, as, as if, as long as, as though, because, before, even if, even though, if, if only, in order that, now that, once, rather than, since, so that, than, that, though, till, unless, until, when, whenever, where, whereas, wherever, while,

A simple coordination with and:

Two other families were also going on this trip, and the parents agreed to look after Amy.

or but (or any other FANBOYS):

Two other families were also going on this trip, but the parents agreed to look after Amy.

You could use a semi-colon:

Two other families were also going on this trip; the parents agreed to look after Amy.

or a semi-colon with in fact:

Two other families were also going on this trip; in fact, the parents agreed to look after Amy.

And if that is not enough, you can also make the first clause dependent on, or relative to, the second.