diff --git a/pywhyllm/suggesters/identification_suggester.py b/pywhyllm/suggesters/identification_suggester.py
index 5cd0d15..f7d7948 100644
--- a/pywhyllm/suggesters/identification_suggester.py
+++ b/pywhyllm/suggesters/identification_suggester.py
@@ -11,9 +11,14 @@ class IdentificationSuggester(IdentifierProtocol):
 
     def __init__(self, llm=None):
         if llm is not None:
-            if (llm == 'gpt-4'):
+            if llm == 'gpt-4':
                 self.llm = guidance.models.OpenAI('gpt-4')
                 self.model_suggester = ModelSuggester('gpt-4')
+            elif isinstance(llm, guidance.models.Model):
+                self.llm = llm
+                self.model_suggester = ModelSuggester(llm)
+            else:
+                raise ValueError("llm must be either 'gpt-4' or a guidance model instance.")
 
     # def suggest_estimand(
     #     self,
diff --git a/pywhyllm/suggesters/model_suggester.py b/pywhyllm/suggesters/model_suggester.py
index b7b9df2..11b7642 100644
--- a/pywhyllm/suggesters/model_suggester.py
+++ b/pywhyllm/suggesters/model_suggester.py
@@ -12,8 +12,12 @@ class ModelSuggester(ModelerProtocol):
 
     def __init__(self, llm=None):
         if llm is not None:
-            if (llm == 'gpt-4'):
+            if llm == 'gpt-4':
                 self.llm = guidance.models.OpenAI('gpt-4')
+            elif isinstance(llm, guidance.models.Model):
+                self.llm = llm
+            else:
+                raise ValueError("llm must be either 'gpt-4' or a guidance model instance.")
 
     def suggest_domain_expertises(
             self,
diff --git a/pywhyllm/suggesters/simple_identification_suggester.py b/pywhyllm/suggesters/simple_identification_suggester.py
index cc404a9..36369eb 100644
--- a/pywhyllm/suggesters/simple_identification_suggester.py
+++ b/pywhyllm/suggesters/simple_identification_suggester.py
@@ -7,8 +7,12 @@ class SimpleIdentificationSuggester:
 
     def __init__(self, llm=None):
         if llm is not None:
-            if (llm == 'gpt-4'):
+            if llm == 'gpt-4':
                 self.llm = guidance.models.OpenAI('gpt-4')
+            elif isinstance(llm, guidance.models.Model):
+                self.llm = llm
+            else:
+                raise ValueError("llm must be either 'gpt-4' or a guidance model instance.")
 
     def suggest_iv(self, factors, treatment, outcome):
         lm = self.llm
diff --git a/pywhyllm/suggesters/simple_model_suggester.py b/pywhyllm/suggesters/simple_model_suggester.py
index d2b130a..26d389f 100644
--- a/pywhyllm/suggesters/simple_model_suggester.py
+++ b/pywhyllm/suggesters/simple_model_suggester.py
@@ -22,8 +22,12 @@ class SimpleModelSuggester:
 
     def __init__(self, llm=None):
         if llm is not None:
-            if (llm == 'gpt-4'):
+            if llm == 'gpt-4':
                 self.llm = guidance.models.OpenAI('gpt-4')
+            elif isinstance(llm, guidance.models.Model):
+                self.llm = llm
+            else:
+                raise ValueError("llm must be either 'gpt-4' or a guidance model instance.")
 
     # new ver
     def suggest_pairwise_relationship(self, variable1: str, variable2: str):
diff --git a/pywhyllm/suggesters/validation_suggester.py b/pywhyllm/suggesters/validation_suggester.py
index dcd0cc5..02904a6 100644
--- a/pywhyllm/suggesters/validation_suggester.py
+++ b/pywhyllm/suggesters/validation_suggester.py
@@ -18,6 +18,10 @@ def __init__(self, llm=None):
         if llm is not None:
             if llm == 'gpt-4':
                 self.llm = guidance.models.OpenAI('gpt-4')
+            elif isinstance(llm, guidance.models.Model):
+                self.llm = llm
+            else:
+                raise ValueError("llm must be either 'gpt-4' or a guidance model instance.")
 
     def suggest_negative_controls(
             self,