1) The lookup you describe should work--especially if set up with a self join relationship. You'll need to make a more detailed description of that (this could be one thread all its own here in the forum) before we could spot why it didn't work for you.
2) I think that you have a many to many relationship here. Am I correct that an Allele can be part of the genome for multiple families and each family can list multiple allele's?
Assuming that I am correct, you'd need something like this:
Families::__pkFamilyID = Family_Allele::_fkFamilyID
Alleles::__pkAlleleID = Family_Allele::_fkAlleleID
You can place a portal to Family_Allele on the Families layout to list and select Alleles records for each given Families record. Fields from Alleles can be included in the Portal to show additional info about each selected Alleles record and the _fkAlleleID field can be set up with a value list for selecting Alleles records by their ID field.
For an explanation of the notation that I am using, see the first post of: Common Forum Relationship and Field Notations Explained
Thanks much for the quick reply. Will study your suggestions and try out in the next couple days.
The self-join relationship (#1) seems to be working now. (I'm not quite sure what I did differently.)
I still can't solve the other look-up problem (#2), in which I want to display data in the Allele table the relevant data that had been entered in the Family table. I think I understand the relationships and nomenclature but it still isn't pulling out all the information I need and the problem seems to be in the Family_Allele table not being able to retrieve the data from its parent Family table (I'm assuming that if this is resolved then the existing portal to Family_Allele in the Allele table will be able to look-up the look-up data).
I've attached a screen shot. The problem relationships are on the left. In the image
"Family_Allele" = "_BreedingLog_Alleles"
"Family" = "_BreedingLog"
"Allele" = "_Fish"
In "_BreedingLog_Alleles", Stock Name, Fertilization, Initials and Date are all set to look-up corresponding fields in "_BreedingLog".
I did set up Allele in "_BreedingLog_Alleles" as a drop down menu (with value list) but I'm not sure how to use this in the look-up feature (or perhaps I misunderstood and I need to use a script to generate the value list?).
I did set up Allele in "_BreedingLog_Alleles" as a drop down menu
While you can use that to link a record in _Fish to a record in _BreedingLog_Alleles that may not be sufficient to do your "look up". Once you have used the join table to link records in _Fish and _BreedingLog, Either a portal to BreedingLog_Alleles or a portal to BreedingLog can be used to display data from the BreedingLog table.
Aggregate data such as a count, sum or average is also possible by defining calculation functions in _Fish that reference fields in _BreedingLog.
If you are using one of these methods and the data is not appearing, then it is most likely the case that the needed join table record with correctly matching values does not exist.