diff --git a/R/all_check_prep.R b/R/all_check_prep.R
index ca5f866..8a58c3a 100644
--- a/R/all_check_prep.R
+++ b/R/all_check_prep.R
@@ -9,8 +9,15 @@ all_checkers <- function(){
     main_defaults <- c(main_defaults, options()$checkers[["goodpractice"]])
   }
 
-  if(length(options()$checkers[["make_pref_pkg_check"]]) > 0){
-    main_defaults <- c(main_defaults, names(options()$checkers[["make_pref_pkg_check"]]))
+  pref_list <- options()$checkers[["make_pref_pkg_check"]]
+  if_then_list <- options()$checkers[["if_this_than_that"]]
+
+  if(length(pref_list) > 0){
+    main_defaults <- c(main_defaults, names(pref_list))
+  }
+
+  if(length(if_then_list) > 0){
+    main_defaults <- c(main_defaults, names(if_then_list))
   }
 
   return(main_defaults)
@@ -24,9 +31,9 @@ all_extra_checkers <- function(){
                         "version_control"=check_version_control)
 
   pref_list <- options()$checkers[["make_pref_pkg_check"]]
+  if_then_list <- options()$checkers[["if_this_than_that"]]
 
   if(length(pref_list) > 0){
-
     for(i in names(pref_list)){
       favored <- pref_list[[i]]$favored
       unfavored <- pref_list[[i]]$unfavored
@@ -34,9 +41,17 @@ all_extra_checkers <- function(){
                                        unfavored = unfavored)
       main_defaults[[i]] <- check_fun
     }
-
   }
 
+  if(length(if_then_list) > 0){
+    for(i in names(if_then_list)){
+      if_this <- if_then_list[[i]]$if_this
+      needs_that <- if_then_list[[i]]$needs_that
+      check_fun <- make_fun_pair_check(fun1 = if_this,
+                                       fun2 = needs_that)
+      main_defaults[[i]] <- check_fun
+    }
+  }
   return(main_defaults)
 }
 
@@ -46,6 +61,7 @@ all_extra_checkers <- function(){
 all_prepers <- function(){
   return(list("scripts" = prep_scripts,
               "version_control" = prep_version_control,
+              "functions" = prep_functions,
               "lintr" = prep_lint_dir,
               "packages" = prep_packages))
 }
diff --git a/inst/extdata/default.yaml b/inst/extdata/default.yaml
index 6805a57..42087dc 100644
--- a/inst/extdata/default.yaml
+++ b/inst/extdata/default.yaml
@@ -1,4 +1,3 @@
-package: "assertthat" #using this package?
 goodpractice:
   ["lintr_assignment_linter",
   "lintr_line_length_linter",
@@ -15,5 +14,8 @@ make_pref_pkg_check:
   JSON:
     favored: jsonlite
     unfavored: rjson
-if_this_than_that: ["gam","gam.check"] #if gam than gam.check
+if_this_than_that:
+  gam:
+    if_this: gam
+    needs_that: gam.check
 comment_threshold: 0.05
diff --git a/tests/testthat/test.R b/tests/testthat/test.R
index ef9d846..d9f75f4 100644
--- a/tests/testthat/test.R
+++ b/tests/testthat/test.R
@@ -29,11 +29,18 @@ test_that("checkers works", {
   expect_type(check_results, "list")
 
   check_xml <- make_pref_pkg_check("XML", "xml2")
-  gp_check(path=system.file("scripts", package="checkers"),
+  pref_package <- gp_check(path=system.file("scripts", package="checkers"),
            checks="XML",
            extra_preps=list(packages=prep_packages),
            extra_checks = list(XML = check_xml))
-
+  expect_type(pref_package, "list")
+
+  check_gam <- make_fun_pair_check("gam", "gam.check")
+  check_funs <- gp_check(path=system.file("scripts", package="checkers"),
+           checks = "check_gam",
+    extra_preps = list(functions = prep_functions),
+    extra_checks = list(check_gam = check_gam))
+  expect_type(check_funs, "list")
 })