data reorganization in r
===

I have following type of data:

    Person <- c("A", "B", "C", "AB", "BC", "AC",  "D", "E")
    Father <- c(NA,  NA,  NA,   "A", "B", "C",    NA, "D")
    Mother <- c(NA,  NA,  NA, "B",   "C", "A", "C",    NA)
    var1 <- c(  1,   2,   3,     4,   2,   1,     6, 9)
    var2 <- c(1.4, 2.3, 4.3,  3.4, 4.2, 6.1,   2.6, 8.2)
    myd <- data.frame (Person, Father, Mother, var1, var2)
    
     Person Father Mother var1 var2
    1      A   <NA>   <NA>    1  1.4
    2      B   <NA>   <NA>    2  2.3
    3      C   <NA>   <NA>    3  4.3
    4     AB      A      B    4  3.4
    5     BC      B      C    2  4.2
    6     AC      C      A    1  6.1
    7      D   <NA>      C    6  2.6
    8      E      D   <NA>    9  8.2

Here is <NA> for missing (unknown). I want re-organize data in to trio (an Individual and its Father and Mother). For example trio for AB individual will include data from from its father A and mother B.

     Person Father Mother var1 var2
    1      A   <NA>   <NA>    1  1.4
    2      B   <NA>   <NA>    2  2.3
    4     AB      A      B    4  3.4

A, B, C can not make trio as they do not have parents. Somecases as E has only one parent father known that is D. In this case there will just two members in the trio.

      7      D   <NA>      C    6  2.6
      3      C   <NA>   <NA>    3  4.3

In case where mother and fathers are repeated in two trios the same value will be recycled. 


Thus expected complete output would be:

        Person Father Mother var1 var2  Trio 
    1      A   <NA>   <NA>    1  1.4     1
    2      B   <NA>   <NA>    2  2.3     1
    4     AB      A      B    4  3.4     1

    2      B   <NA>   <NA>    2  2.3     2
    3      C   <NA>   <NA>    3  4.3     2
    5     BC      B      C    2  4.2     2

    1      A   <NA>   <NA>    1  1.4     3
    3      C   <NA>   <NA>    3  4.3     3
    6     AC      C      A    1  6.1     3
  
    NA       <NA> <NA>    <NA>  NA  NA     4
    3      C   <NA>   <NA>    3  4.3      4
    7      D   <NA>      C    6  2.6      4

    NA       <NA> <NA>    <NA>  NA  NA     5
    7      D   <NA>      C      6  2.6     5
    8      E      D   <NA>      9  8.2     5     
