Joining two RDD's in PySpark?

Question

I asked a previous question regarding two RDD's I was trying to join together, here were the two RDD's:

+------+---+
|    _1| _2|
+------+---+
|Python| 36|
|     C|  6|
|    C#|  8|
+------+---+

+------+---+
|    _1| _2|
+------+---+
|Python| 10|
|     C|  1|
|    C#|  1|
+------+---+

After executing the following line of code on both RDD's, this was the result:

joined_rdd = rdd1.join(rdd2).map(lambda x: (x[0], *x[1]))

+------+---+---+
|    _1| _2| _3|
+------+---+---+
|Python| 36| 10|
|     C|  6|  1|
|    C#|  8|  1|
+------+---+---+

This was exactly what I wanted, BUT, if I would like to join another RDD to this 3 column joined_rdd, how might I do that? The code I used originally does not work and I've tried every variation and cannot seem to obtain the result I want, here is what I want it to look like:

rdd3
+------+---+
|    _1| _2|
+------+---+
|Python|  8|
|     C| 15|
|    C#|100|
+------+---+

After joining with joined_rdd:

final_joined_rdd
+------+---+---+---+
|    _1| _2| _3| _3|
+------+---+---+---+
|Python| 36| 10|  8|
|     C|  6|  1| 15|
|    C#|  8|  1|100|
+------+---+---+---+

Any help to achieve this result would be appreciated, thanks!

Note: I cannot convert these RDD's to data frame and then join because the RDD's are really just DStream objects.