unfortunately, you can't combine dry and wet clay - attaching clay works
best when they're both the same consistency. Now, you could cheat, I
suppose as I've done in the past and it sometimes works! Try spraying or
even get a wet enough sponge or rag and set it on the dry clay where you'd
like to connect the clay, then cover with plastic...and leave it
overnight. This should soften it enough to go back and slip and score
together your pieces. Sometimes it works, sometimes it doesn't!