Few R functions to help to manage the pedigree records.
kinship.make.ped is function to convert the normal pedigree records to a format needed by Kinship2 package in R.
original pedigree records structure: 11 22 33 pedigree format of kinship2: 22 NA NA 33 NA NA 11 22 33

kinship.ancestor.standard is the function to extract the given generations of ancestors of the given individual.

kinship.descendant.standard is the function to extract the given number of generations descendants of a given individual.

kinship.sibling.standard is a function to find all the siblings and half-siblings of a given individual.

kinship.mate is a function to find all the individuals mated with a given individual.

By playing around with these functions, you can manage you pedigree and generate pedigrees of individuals you are interested in in a big pedigree which is not possible to plot out. For instance, if you would like to plot all the descendants of all sibling and half-sibling of a targeted individual, you could achieve it like this:
individual<-ped$individual
fa<-ped$sire
mo<-ped$dam
sibling<-kinship.sibling.standart(id,individual,fa,mo)

extract the descendants of all siblings

sibling_descent_all<-data.frame()
for (i in sibling[,1] ) {
sibling_descent<-kinship.descendant.standard(i,g=1,individual,fa,mo)
sibling_descent_all<-rbind(sibling_descent_all,sibling_descent)
}
sibling_descent_all<-unique(sibling_descent_all)

if you would like to add a few generation of ancestor as well, you could use kinship.ancestor.standard(g,id,individual,fa,mo) function

find founders

sibling_descent_all<-kinship.make.ped(indidvidual,fa,mo)

then add the sex, affection and other information. remove the duplicates, then it is ready for the pedigree() function of Kinship2 package.