diff --git a/R/createTableOfRDBESIds.r b/R/createTableOfRDBESIds.r
index 4431d35..0ba86b1 100644
--- a/R/createTableOfRDBESIds.r
+++ b/R/createTableOfRDBESIds.r
@@ -1,3 +1,4 @@
+
 #' Create a table of RDBES Ids
 #'
 #' examples for now see
@@ -18,51 +19,119 @@
 #' myTableOfIds<- createTableOfRDBESIds(myH1RawObject)
 #' }
 
-createTableOfRDBESIds<-function(x, addSAseqNums=TRUE)
-{
+createTableOfRDBESIds<-function(x, addSAseqNums=TRUE){
 
-# note: needs developments for different lower hierarchies
+  # note: needs developments for different lower hierarchies
 
-# x is RDBESobj
-# hierarchy is hierarchy (integer)
-# outputs a table with ids for matching
+  # x is x
+  # hierarchy is hierarchy (integer)
+  # outputs a table with ids for matching
 
+  #libraries
+  require(data.table)
 
-CStableNames<- getTablesInRDBESHierarchy(hierarchy = x$DE$DEhierarchy[1],
-                                      includeOptTables = FALSE,
-                                      includeLowHierTables = TRUE,
-                                      includeTablesNotInSampHier = FALSE)
+  CStableNames<- getTablesInRDBESHierarchy(hierarchy = x$DE$DEhierarchy[1],
+                                           includeOptTables = FALSE,
+                                           includeLowHierTables = TRUE,
+                                           includeTablesNotInSampHier = FALSE)
 
-for (i in 1:(length(CStableNames)-1))
-{
-id_1<-paste0(CStableNames[i],"id")
-id_2<-paste0(CStableNames[i+1],"id")
-if (i==1) df_1<-data.frame(x[[CStableNames[i]]][,list(get(id_1))]); colnames(df_1)<-id_1
-if((CStableNames[i+1] == "SA" & addSAseqNums == TRUE) | CStableNames[i+1] %in% c("BV")){
-							if(CStableNames[i+1]=="SA") {df_2<-data.frame(x[[CStableNames[i+1]]][,list(get(id_1), get(id_2), get("SAseqNum"), get("SAparSequNum"))]); colnames(df_2)<-c(id_1,id_2,"SAseqNum","SAparSequNum")}
-							if(CStableNames[i+1]=="BV") {df_2<-data.frame(x[[CStableNames[i+1]]][,list(get(id_1), get(id_2), get("BVfishId"))]); colnames(df_2)<-c(id_1,id_2,"BVfishId")}
-							} else {
-								df_2<-data.frame(x[[CStableNames[i+1]]][,list(get(id_1), get(id_2))]); colnames(df_2)<-c(id_1,id_2)
-								}
+  for (i in 1:(length(CStableNames)-1)){
+    cat("Processing", CStableNames[i], "table. \n")
+    cat("Merging", CStableNames[i], " with ", CStableNames[i+1], " tables. \n")
+    id_1<-paste0(CStableNames[i],"id")
+    id_2<-paste0(CStableNames[i+1],"id")
 
-if (i==1) out<-merge(df_1,df_2, all.x=T) else out<-merge(out, df_2, all.x=T)
+    if(i==1){
+      cat("Using", id_1, " from ", CStableNames[i], "table and", id_2, " from ", CStableNames[i+1], "table. \n")
+      df_1<-data.frame(x[[CStableNames[i]]][,list(get(id_1))]); colnames(df_1)<-id_1
+    }
 
-#colnames(out)<-c(id_1,id_2)
+    if((CStableNames[i+1] == "SA" & addSAseqNums == TRUE) | CStableNames[i+1] %in% c("BV")){
 
-}
-# reorders
-if(addSAseqNums==TRUE){
-	out<-out[,c(paste0(CStableNames,"id"),"BVfishId","SAseqNum","SAparSequNum")]
-	} else {
-		out<-out[,c(paste0(CStableNames,"id"),"BVfishId")]
+      if(CStableNames[i+1]=="SA"){
 
+        cat("Using", id_1, " from ", CStableNames[i], "table and", id_2, "SAseqNum, and SAparSequNum from ", CStableNames[i+1], "table. \n")
+        df_2<-data.frame(x[[CStableNames[i+1]]][,list(get(id_1), get(id_2), get("SAseqNum"), get("SAparSequNum"))]); colnames(df_2)<-c(id_1,id_2,"SAseqNum","SAparSequNum")
 
-		}
-out
-}
+      }
+
+      if(CStableNames[i+1]=="BV"){
+
+        cat("Using", id_1, " from ", CStableNames[i], "table and", id_2, "and BVfishId from ", CStableNames[i+1], "table. \n")
+        df_2<-data.frame(x[[CStableNames[i+1]]][,list(get(id_1), get(id_2), get("BVfishId"))]); colnames(df_2)<-c(id_1,id_2,"BVfishId")
+        # We also need a reference reporting the SAid, for when the lower hierarchy is C, see below.
+        df_2C<-data.frame(x[[CStableNames[i+1]]][,list(get("SAid"), get(id_1), get(id_2),get("BVfishId"))]); colnames(df_2C)<-c("SAid", id_1,id_2,"BVfishId")
+
+      }
+
+    }else{
+
+      cat("Using", id_1, " from ", CStableNames[i], "table and", id_2, " from ", CStableNames[i+1], "table. \n")
+      df_2<-data.frame(x[[CStableNames[i+1]]][,list(get(id_1), get(id_2))]); colnames(df_2)<-c(id_1,id_2)
+
+    }
+
+    if (i==1){
+
+      out<-merge(df_1,df_2, all.x=T)
+
+    }else{
+
+      if(CStableNames[i+1]=="BV"){
+
+        # The lower hierarchy (A:D) implies that FM is used or not.
+        # Due to this, we need to do a conditional merging by either FMid (where present) or SAid.
+        outTmp = merge(out, x$SA[,c("SAid","SAlowHierarchy")])
+
+        # Convert to data.table if not already
+        setDT(outTmp)
+        setDT(out)
+        setDT(df_2)
+        setDT(df_2C)
+
+        # Filter and get SAid groups
+        keepA <- outTmp[SAlowHierarchy == "A", SAid]
+        keepB <- outTmp[SAlowHierarchy == "B", SAid]
+        keepC <- outTmp[SAlowHierarchy == "C", SAid]
+        keepD <- outTmp[SAlowHierarchy == "D", SAid]
 
-# e.g.,
- ## default adds "SAseqNum","SAparSequNum"
- #head(createTableOfRDBESIds(x = RDBESprepObj))
- ## if addSAseqNums is set to FALSE, "SAseqNum" and "SAparSequNum" are not added to output
- # head(createTableOfRDBESIds(x = RDBESprepObj, addSAseqNums=FALSE))
+        # Split 'out' accordingly
+        toMergeA <- out[SAid %in% keepA]
+        toMergeB <- out[SAid %in% keepB]
+        toMergeC <- out[SAid %in% keepC]
+        toMergeD <- out[SAid %in% keepD]
+
+        # Conditional merges
+        mergedA <- df_2[toMergeA, on = "FMid"]              # left join equivalent (all.x = TRUE)
+        mergedB <- df_2[toMergeB, on = "FMid"]              # same for group B
+        mergedC <- df_2C[toMergeC, on = "SAid", nomatch = 0][, .SD, .SDcols = c(names(toMergeC), "BVid","BVfishId")]
+        mergedD <- toMergeD                                 # unchanged group D
+
+        # Combine back
+        out <- rbindlist(list(mergedA, mergedB, mergedC, mergedD), use.names = TRUE, fill = TRUE)
+
+      }else{
+
+        out<-merge(out, df_2, all.x=T)
+
+      }
+
+    }
+  }
+
+  out <- as.data.frame(out)
+
+    # reorders
+  if(addSAseqNums==TRUE){
+
+    out<-out[,c(paste0(CStableNames,"id"),"BVfishId","SAseqNum","SAparSequNum")]
+
+  } else {
+
+    out<-out[,c(paste0(CStableNames,"id"),"BVfishId")]
+
+  }
+
+  out
+
+}