Software to generate random trees with specific constraints

[basm101]

Hello,

Which software is best for generating random trees given a constraints 
tree that defines the major subgroups ?

I tried using paup, but I cannot generate all trees as I have way too 
many. If I try using the random command plus specifying 100 trees it 
says I cant use my constraints :(

ie.

generatetrees random constraints=allgroups ntrees=100;
(where allgroups is my constraints tree included in the paup block)
doesnt work.

I know there must be lots of software that could do this - suggestions 
please !

basm101

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