When I look using SSMS, I can see the SSIS dtsx package being called for each of our customers, using a parameter called NetworkInternalCode. It appears that that value is passed to the package by the Project calling it.
$ssisProject = $Ssiscatalog.Folders[$FolderName].Projects[$ProjectName]
$ssisProject.Parameters
Shows this, see below, and it's the value of that NetworkInternalCode that is passed to '$PackageName = 'MasterETL.dtsx'' that I want to find for each time it is run.
Name : NetworkInternalCode
Id : 135794
ProjectId : 11
ObjectType : 20
ObjectName : mycompany.ETL.Exports
DataType : String
Required : False
Sensitive : False
Description: MAKE SURE to leave as EMPTY string BEFORE merge
DesignDefaultValue :
DefaultValue :
ValueType : Literal
ValueSet : False
ReferencedVariableName :
ValidationStatus : N
IdentityKey: ParameterInfo[@Name='NetworkInternalCode']
Urn: IntegrationServices[@Name='ETLSRV\PROD']/Catalog[@Name='SSISDB']/CatalogFolder[@Name='mycompany_Exports']/ProjectInfo[@Name='mycompany.E
TL.Exports']/ParameterInfo[@Name='NetworkInternalCode']
Properties : {Name=Name/Type=System.String/Writable=False/Value=NetworkInternalCode, Name=Id/Type=System.Int64/Writable=False/Value=135794,
Name=ProjectId/Type=System.Int64/Writable=False/Value=11, Name=ObjectType/Type=System.Int16/Writable=False/Value=20...}
Metadata : Microsoft.SqlServer.Management.Sdk.Sfc.Metadata.SfcMetadataDiscovery
Parent : ProjectInfo[@Name='mycompany.ETL.Exports']